Interactions on record — worth a quick check against your medications. Based on 5 of 6 ingredients. Check your meds →
Dietary supplement

UT Answer Ingredients & Drug Interactions

by Nature's Answer

UT Answer label
See full label image
Capsule Category: Botanical With Nutrients
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking UT Answer against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

UT Answer is a dietary supplement by Nature's Answer with 6 active ingredients. Its ingredients are commonly taken for common cold and immune support, antioxidant support, skin health and collagen formation.Based on those ingredients, 1,078 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Uva Ursi (Arctostaphylos uva-ursi) leaf extract, VitaCran Cranberry (Vaccinium macrocarpon) fruit powder, Caprylic Acid. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against UT Answer by Nature's Answer

Ask about any prescription or over-the-counter medication and we check it for interactions with UT Answer by Nature's Answer — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of UT Answer by Nature's Answer

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 5 of its 5 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

UT Answer contains five active ingredients. Vitamin C is included to support immune health and general wellness.

D-mannose is a simple sugar that may be intended for urinary tract support. Caprylic acid is a fatty acid sometimes used in herbal formulations.

VitaCran Cranberry powder (from Vaccinium macrocarpon fruit) and uva ursi leaf extract (from Arctostaphylos uva-ursi) are both traditional botanicals — cranberry is commonly used for urinary health, and uva ursi has a history of use for the same purpose. The capsules also contain vegetable capsule material and calcium silicate as inactive ingredients.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: Urinary tract health support.
  • We looked for evidence on: Kidney stones (nephrolithiasis), Urinary tract infection, Bladder health, Urinary discomfort.
  • The strongest evidence on file: Cranberry is rated "Possibly Effective" for Urinary tract infections (UTIs) (Natural Medicines).
  • Also on file: Uva Ursi is rated "Possibly Ineffective" for Urinary tract infections (UTIs).
  • Also on file: D-mannose is rated "Possibly Ineffective" for Urinary tract infections (UTIs).

For vitamin C, the data shows it's effective for vitamin C deficiency itself, and possibly effective for anemia of chronic disease, atrial fibrillation, cataracts, and exercise-related respiratory infections. D-mannose is likely effective for a rare genetic condition called carbohydrate-deficient glycoprotein syndrome type 1b, but only possibly ineffective for urinary tract infections — meaning the evidence doesn't support its use there.

Caprylic acid has insufficient evidence to rate for epilepsy or essential tremor. Cranberry is possibly effective for urinary tract infections, but the evidence for age-related cognitive decline, prostate health, cancer prevention, and other conditions is insufficient.

Uva ursi is only possibly ineffective for urinary tract infections, with insufficient evidence for bronchitis and prostate conditions.

The evidence, ingredient by ingredient Vitamin C D-mannose Caprylic Acid Cranberry Uva Ursi

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 5 of the 5 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 5 of 5.
  • General safety write-ups exist for 5 of 5.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin C is generally well tolerated at normal dietary doses, but very high doses can cause side effects — mainly abdominal cramps, heartburn, diarrhea, nausea, and vomiting at doses above 2 grams daily. Kidney stones have been reported in people prone to them.

D-mannose seems well tolerated short-term, though long-term safety data are limited; common side effects include bloating, diarrhea, and nausea. Caprylic acid is generally recognized as safe in food amounts but is less well studied at supplement doses; mild abdominal discomfort and taste changes can occur.

Cranberry is generally well tolerated but concentrated supplements are less studied than food amounts; diarrhea and gastrointestinal discomfort are the most common effects. Uva ursi may be used short-term but can be toxic at high doses or with long-term use — side effects include nausea, vomiting, diarrhea, and stomach upset, and at very high doses (20+ grams), serious effects like convulsions and delirium have been reported.

Side effects, ingredient by ingredient Vitamin C D-mannose Caprylic Acid Cranberry Uva Ursi

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 4 of the 5 matched ingredients can interact with medications — Uva Ursi, Cranberry, Vitamin C, Caprylic Acid.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; cancer treatments; lithium.
  • For scale: 1,079 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check with your pharmacist before taking this product if you use blood thinners like warfarin (vitamin C and cranberry can affect them), birth control or hormone replacement therapy (vitamin C may raise estrogen levels), chemotherapy drugs (vitamin C may reduce their effectiveness), cholesterol medications especially atorvastatin (cranberry), blood pressure drugs (caprylic acid and cranberry), antipsychotics like fluphenazine (vitamin C), HIV medications like indinavir (vitamin C), thyroid medication like levothyroxine (vitamin C), lithium (uva ursi may raise levels), or NSAIDs (caprylic acid and cranberry). The interaction data for cranberry and uva ursi with liver enzyme systems spans many other drugs — run your complete medication list through the checker below to be sure.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

UT Answer is a multi-ingredient supplement that interacts with numerous medications, particularly blood thinners, hormonal drugs, chemotherapy, and drugs processed through your liver's enzyme systems. If you take any prescription medication, especially warfarin, birth control, psychiatric drugs, or antiretroviral therapy, check your exact drugs with the tool on this page before starting.

Talk to your pharmacist or doctor about whether this product is right for you, particularly if you're pregnant, breastfeeding, or prone to kidney stones.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 5 of 5 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jan 7, 2019.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about UT Answer, straight from the product label.

Brand Nature's Answer
Barcode (UPC) 083000263750
Net contents 90 Vegetarian Capsule(s)
Market status On market
Date entered into DSLD Jan 7, 2019
DSLD ID 185086
Product type Botanical With Nutrients
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Gluten Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for UT Answer by Nature's Answer, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
3 Capsule(s)
Maximum serving Sizes:
3 Capsule(s)
Servings per container
30
UPC/BARCODE
083000263750
IngredientAmount% DV
Calories5 Calorie(s)--
Total Carbohydrates2 Gram(s)1%
Sugar2 Gram(s)--
Vitamin C30 mg50%
D-Mannose1450 mg--
Caprylic Acid250 mg--
VitaCran Cranberry (Vaccinium macrocarpon) fruit powder175 mg--
Uva Ursi (Arctostaphylos uva-ursi) leaf extract50 mg--

Other ingredients: Vegetable Capsule, Calcium Silicate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Brand IP Statement(s)

Discover Nature's Answer and trust the Difference... The True Nature of Our Standards goes way beyond the herb...

Discover Nature's Answer

VitaCran is a registered trademark of VDF FutureCeuticals, Inc, used under license.

2017 Nature's Answer

Precautions

Warning: Keep Out of Reach of Children.

Do not use if safety seal is damaged or missing.

If you are pregnant, nursing, taking any medications, planning any medical procedure or have a medical condition, consult with your healthcare practitioner before use.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Storage

Store in a cool, dry place.

Seals/Symbols

Gluten Free

General Statements

New Easy-to-take Capsules Since 1972

Healthy urinary tract support program 1,955 Per Serving

Formula

Powered by D-Mannose

FDA Statement of Identity

Dietary Supplement

Formulation

Gluten-Free

Vegetarian/Vegan

Suggested/Recommended/Usage/Directions

Suggested Use: As a dietary supplement, for intensive use 3 day regimen: Day 1: 4 servings (12 capsules) spread throughout the day. Day 2: 3 servings (9 capsules) spread throughout the day. Day 3: 2 servings (6 capsules) spread throughout the day. For long term use, as a dietary supplement, take 1 serving (3 capsules) 1-2 times spread throughout the day. May be taken with water or food.

General

27375 Rev. 117

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

UT Answer by Nature's Answer label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

UT Answer label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in UT Answer by Nature's Answer

These are the 6 active ingredients this product is made of. Select any to open its full monograph.

Serving size3 Capsule(s) Dosage formCapsule Servings per container30 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Sugar

2 Gram(s) per serving

Vitamin C

Interacts with
207 drugs
30 mg per serving Form: Ascorbic Acid

Vitamin C (ascorbic acid) is an essential nutrient your body needs but cannot make, so you must get it from food or supplements. It's important for im...

Vitamin C monograph & interactions

D-Mannose

No known
interactions
1450 mg per serving

D-mannose is a natural sugar most often used to help prevent urinary tract infections, especially those caused by E. coli. Early research is promising...

D-Mannose monograph & interactions

Caprylic Acid

Interacts with
262 drugs
250 mg per serving Form: Magnesium Caprylate

Caprylic acid is a medium-chain fatty acid found in coconut oil and palm kernel oil that is popularly used for yeast overgrowth and gut health. While...

Caprylic Acid monograph & interactions

VitaCran Cranberry (Vaccinium macrocarpon) fruit powder

Interacts with
712 drugs
175 mg per serving

Cranberry is best known for helping to prevent repeated urinary tract infections (UTIs) in some people, and the evidence here is moderate but mixed. I...

VitaCran Cranberry (Vaccinium macrocarpon) fruit powder monograph & interactions

Uva Ursi (Arctostaphylos uva-ursi) leaf extract

Interacts with
803 drugs
50 mg per serving

Uva ursi is a traditional herb used mainly for urinary tract infections, and its leaves contain a compound called arbutin that may have antimicrobial...

Uva Ursi (Arctostaphylos uva-ursi) leaf extract monograph & interactions

Other (inactive) ingredients: Vegetable Capsule, Calcium Silicate. These complete the product’s ingredient list but are not active constituents.

Interaction report

UT Answer by Nature's Answer Drug Interactions

Want to check YOUR meds against UT Answer?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
1,078Drugs
991 Moderate 87 Minor

Ingredients driving the most interactions

Uva Ursi (Arctostaphylos uva-ursi) leaf extract 803
VitaCran Cranberry (Vaccinium macrocarpon) fruit powder 712
Caprylic Acid 262
Vitamin C 207

Individual Drug Interactions

The ingredients in UT Answer interact with 1,078 drugs. Click any drug to see the details.

4 of the 6 ingredients in UT Answer interact with drugs. Each result below shows which ingredient is responsible. Uva Ursi (Arctostaphylos uva-ursi) leaf extract VitaCran Cranberry (Vaccinium macrocarpon) fruit powder Caprylic Acid Vitamin C

Each ingredient & the kinds of drugs it affects

For each ingredient in UT Answer with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Uva Ursi (Arctostaphylos uva-ursi) leaf extract6 drug types · 803 drugs

Cytochrome P450 2C19 (Cyp2C19) Substrates

Theoretically, uva ursi may decrease the metabolism of CYP2C19 substrates.
In vitro, uva ursi appears to inhibit cytochrome CYP2C19. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, uva ursi may decrease the metabolism of CYP3A4 substrates.
In vitro, uva ursi appears to inhibit CYP3A4. This effect has not been reported in humans.

Likelihood Possible Evidence D
Glucuronidated Drugs

Theoretically, uva ursi may increase levels of drugs metabolized by glucuronidation.
In vitro, uva ursi extract appears to strongly inhibit UDP-glucuronosyltransferase (UGT) 1A1 (UGT1A1). However, uva ursi extract does not appear to inhibit UGT1A1 in animal models. This effect has not been reported in humans.

Likelihood Possible Evidence D
Lithium

Theoretically, uva ursi may increase lithium levels, necessitating a decrease in dose.
Uva ursi may have diuretic properties. Diuretics may increase lithium reabsorption with sodium in the proximal tubule of the kidney. Theoretically, uva ursi might reduce excretion and increase levels of lithium.

Likelihood Probable Evidence D
Urinary Acidifying Agents

Effects of uva ursi in the urinary tract may be reduced by urinary acidifying agents.
Uva ursi seems to work best in alkaline urine. Theoretically, taking uva ursi with medications known to acidify the urine may decrease any effects of uva ursi on the urinary tract.

Likelihood Possible Evidence D
P-Glycoprotein Substrates

Theoretically, uva ursi may alter the levels of drugs transported by P-glycoprotein.
In vitro, uva ursi appears to inhibit the multi-drug transporter protein, P-glycoprotein. This effect has not been reported in humans.

Likelihood Possible Evidence D
Uva Ursi (Arctostaphylos uva-ursi) leaf extract full monograph & interactions

VitaCran Cranberry (Vaccinium macrocarpon) fruit powder6 drug types · 712 drugs

Atorvastatin (Lipitor)

Theoretically, cranberry might increase levels and adverse effects of atorvastatin.
In one case report, a patient taking atorvastatin experienced upper back pain, rhabdomyolysis, and abnormal liver function after drinking cranberry juice 16 ounces daily for 2 weeks. Theoretically, this may have been caused by inhibition of cytochrome P450 3A4 (CYP3A4) enzymes by cranberry juice, as atorvastatin is a CYP3A4 substrate. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice. Patients taking atorvastatin should avoid large quantities of cranberry juice.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, cranberry might increase the levels and adverse effects of CYP3A4 substrates.
A case of upper back pain, rhabdomyolysis, and abnormal liver function has been reported for a patient taking atorvastatin, a CYP3A4 substrate, in combination with cranberry juice 16 ounces daily for 2 weeks. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice. Also, animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine, a CYP3A4 substrate, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control.

Likelihood Possible Evidence D
Nifedipine (Procardia)

Theoretically, cranberry might increase the levels and adverse effects of nifedipine.
Animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine treatment, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, cranberry might increase the levels and adverse effects of warfarin. However, research is conflicting.
There is contradictory evidence about the effect of cranberry juice on warfarin. Case reports have linked cranberry juice consumption to increases in the international normalized ratio (INR) in patients taking warfarin, resulting in severe spontaneous bleeding and excessive postoperative bleeding. Daily consumption of cranberry sauce for one week has also been linked to an increase in INR in one case report. In a small study in healthy young males, taking a high dose of 3 grams of cranberry juice concentrate capsules, equivalent to 57 grams of fruit daily, for 2 weeks produced a 30% increase in the area under the INR-time curve after a single 25-mg dose of warfarin. However, 3 very small clinical studies in patients stabilized on warfarin reported that cranberry juice 250 mL once or twice daily for 7 days (27% cranberry juice or pure cranberry juice) or 240 mL once daily for 14 days does not significantly increase INR or affect plasma warfarin levels. The reasons for these discrepant findings are unclear. It is possible that the form and dose of cranberry may play a role, as cranberry extracts and juices contain different constituents. Additionally, an in vitro study evaluating 5 different cranberry juices found varying effects, with only a cranberry concentrate, and not diluted cranberry juices, inhibiting CYP2C9. However, this concentrate did not inhibit CYP2C9 activity in humans.

Likelihood Possible Evidence B
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, cranberry might increase the levels and adverse effects of CYP2C9 substrates. However, research is conflicting.
There is contradictory evidence about the effect of cranberry on CYP2C9 enzymes. In vitro evidence suggests that flavonoids in cranberry inhibit CYP2C9 enzymes. However, clinical research shows that cranberry juice does not significantly affect the levels, metabolism, or elimination of the CYP2C9 substrates flurbiprofen or diclofenac. Also, in patients stabilized on warfarin, drinking cranberry juice 250 mL daily for 7 days does not significantly increase the anticoagulant activity of warfarin, a CYP2C9 substrate. Additional pharmacokinetic research shows that cranberry juice does not increase peak plasma concentrations or area under the concentration-time curve of warfarin.

Likelihood Unlikely Evidence B
Diclofenac (Voltaren, Others)

Theoretically, cranberry might modestly increase the levels and adverse effects of diclofenac.
In vitro evidence suggests that cranberry juice inhibits diclofenac metabolism by human liver microsomes. However, drinking cranberry juice does not seem to affect diclofenac metabolism in humans.

Likelihood Unlikely Evidence B
VitaCran Cranberry (Vaccinium macrocarpon) fruit powder full monograph & interactions

Caprylic Acid3 drug types · 262 drugs

Antihypertensive Drugs

Theoretically, caprylic acid might increase the risk of hypotension when used with antihypertensive drugs.
Animal research suggests that caprylic acid might have positive inotropic effects, resulting in reduced arterial pressure and vascular resistance and increased cardiac output.

Likelihood Possible Evidence D
Nonsteroidal Anti-Inflammatory Drugs (Nsaids)

Theoretically, caprylic acid might increase plasma concentrations of NSAIDs.
In vitro research suggests that caprylic acid might displace NSAIDs from binding sites on albumin. This effect has not been reported in humans.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, caprylic acid might increase plasma concentrations of warfarin.
In vitro research suggests that high doses of caprylic acid might displace warfarin from albumin binding sites. This effect has not been reported in humans.

Likelihood Possible Evidence D
Caprylic Acid full monograph & interactions

Vitamin C13 drug types · 207 drugs

Alkylating Agents

Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals, such as cyclophosphamide, chlorambucil, carmustine, busulfan, and thiotepa. In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Aluminum

Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Research in animals and humans shows that vitamin C increases aluminum absorption, theoretically by chelating aluminum and keeping it in solution where it is available for absorption. In people with normal renal function, urinary excretion of aluminum will likely increase, making aluminum retention and toxicity unlikely. Patients with renal failure who take aluminum-containing compounds such as phosphate binders should avoid vitamin C supplements in doses above the recommended dietary allowances.

Likelihood Probable Evidence B
Antitumor Antibiotics

Theoretically, the antioxidant effects of vitamin C might reduce the effectiveness of antitumor antibiotics.
The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs which generate free radicals, such as doxorubicin. In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells. More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on chemotherapy.

Likelihood Possible Evidence D
Estrogens

Vitamin C might increase blood levels of estrogens.
Increases in plasma estrogen levels of up to 55% occur under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products. It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall. When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. Increases in plasma estrogen levels may occur when patients who are deficient in vitamin C take supplements. Monitor these patients for estrogen-related side effects.

Likelihood Probable Evidence B
Fluphenazine (Prolixin)

Theoretically, vitamin C might decrease levels of fluphenazine.
In one patient there was a clinically significant decrease in fluphenazine levels when vitamin C (500 mg twice daily) was started. The mechanism is not known, and there is no further data to confirm this interaction.

Likelihood Possible Evidence D
Indinavir (Crixivan)

Vitamin C can modestly reduce indinavir levels.
One pharmacokinetic study shows that taking vitamin C 1 gram orally once daily along with indinavir 800 mg orally three times daily reduces the area under the concentration-time curve of indinavir by 14%. The mechanism of this interaction is unknown, but it is unlikely to be clinically significant in most patients. The effect of higher doses of vitamin C on indinavir levels is unknown.

Likelihood Probable Evidence B
Levothyroxine (Synthroid, Others)

Vitamin C can increase levothyroxine absorption.
Two clinical studies in adults with poorly controlled hypothyroidism show that swallowing levothyroxine with a glass of water containing vitamin C 500-1000 mg in solution reduces thyroid stimulating hormone (TSH) levels and increases thyroxine (T4) levels when compared with taking levothyroxine alone. This suggests that vitamin C increases the oral absorption of levothyroxine, possibly due to a reduction in pH.

Likelihood Probable Evidence B
Warfarin (Coumadin)

High-dose vitamin C might reduce the levels and effectiveness of warfarin.
Vitamin C in high doses may cause diarrhea and possibly reduce warfarin absorption. There are reports of two people who took up to 16 grams daily of vitamin C and had a reduction in prothrombin time. Lower doses of 5-10 grams daily can also reduce warfarin absorption. In many cases, this does not seem to be clinically significant. However, a case of warfarin resistance has been reported for a patient who took vitamin C 500 mg twice daily. Cessation of vitamin C supplementation resulted in a rapid increase in international normalized ratio (INR). Tell patients taking warfarin to avoid taking vitamin C in excessively high doses (greater than 10 grams daily). Lower doses may be safe, but the anticoagulation activity of warfarin should be monitored. Patients who are stabilized on warfarin while taking vitamin C should avoid adjusting vitamin C dosage to prevent the possibility of warfarin resistance.

Likelihood Possible Evidence D
Acetaminophen (Tylenol, Others)

High-dose vitamin C might slightly prolong the clearance of acetaminophen.
A small pharmacokinetic study in healthy volunteers shows that taking high-dose vitamin C (3 grams) 1.5 hours after taking acetaminophen 1 gram slightly increases the apparent half-life of acetaminophen from around 2.3 hours to 3.1 hours. Ascorbic acid competitively inhibits sulfate conjugation of acetaminophen. However, to compensate, elimination of acetaminophen glucuronide and unconjugated acetaminophen increases. This effect is not likely to be clinically significant.

Likelihood Probable Evidence B
Aspirin

Acidification of the urine by vitamin C might increase aspirin levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction is not clinically significant.

Likelihood Possible Evidence B
Choline Magnesium Trisalicylate (Trilisate)

Acidification of the urine by vitamin C might increase choline magnesium trisalicylate levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction probably is not clinically significant.

Likelihood Possible Evidence B
Niacin

Vitamin C might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.
A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease. It is not known whether this adverse effect is due to a single antioxidant such as vitamin C, or to the combination. It also is not known whether it will occur in other patient populations.

Likelihood Possible Evidence A
Salsalate (Disalcid)

Acidification of the urine by vitamin C might increase salsalate levels.
It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels. However, short-term use of up to 6 grams/day vitamin C does not seem to affect urinary pH or salicylate excretion, suggesting this interaction probably is not clinically significant.

Likelihood Possible Evidence B
Vitamin C full monograph & interactions
The maker

Brand information

Manufacturer and brand details for UT Answer, from the product label.

Nature's Answer

See all Nature's Answer products
Name
Nature's Answer
Street Address
85 Commerce Drive
City
Hauppauge
State
NY
ZipCode
11788
Phone Number
(800) 439-2324
Web Address
www.naturesanswer.com
Pharmacist Counseling Corner

UT Answer by Nature's Answer: Common Questions

Does UT Answer by Nature's Answer interact with any medications?
Yes. Based on its ingredients, UT Answer has a known interaction with 1,078 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
UT Answer contains 6 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Will this help my urinary tract infections?
Cranberry in this product is possibly effective for UTIs based on available evidence, meaning some studies support its use but findings are mixed. Uva ursi, also included, is only possibly ineffective — the data don't support it for this purpose. Neither ingredient is a substitute for medical treatment if you have an active infection; see your doctor or pharmacist.
Can I take this if I'm pregnant?
It depends on which ingredient we're talking about. Vitamin C at normal supplement doses is likely safe, but high doses should be avoided unless your doctor says otherwise. Cranberry is likely safe. However, uva ursi should be avoided during pregnancy because it may stimulate the uterus and safety data are incomplete. Talk with your doctor before starting, especially given the vitamin C and uva ursi concerns.
What side effects might I get?
The most common are digestive: bloating, diarrhea, nausea, stomach upset, and vomiting — these can come from D-mannose, caprylic acid, cranberry, or uva ursi. Vitamin C at high doses may cause heartburn, abdominal cramps, or headache. Uva ursi at very high doses (20+ grams) can cause serious effects like convulsions, but normal use is generally mild. Most people tolerate these short-term without problems.
How much vitamin C is in this, and is it safe?
The product facts don't state the exact dose of vitamin C per capsule, so check the label. At normal dietary amounts and standard supplement doses, vitamin C is generally well tolerated. High doses above 2 grams daily increase the risk of side effects like diarrhea and kidney stones (especially if you're prone to them). Ask your pharmacist what dose is in this product.
Is this a substitute for antibiotics if I have a UTI?
No. While cranberry is possibly effective for UTI prevention or mild symptoms, this product is not a substitute for medical treatment of an active infection. If you have a UTI, see your doctor — you may need antibiotics. These ingredients are intended for general urinary health support, not to treat infection.
Can I take this long-term?
The safety data suggest caution with long-term use of uva ursi — it's intended for short-term use and can be toxic with prolonged high doses. D-mannose safety data long-term are limited. Vitamin C and cranberry seem better tolerated longer-term at normal doses, but discuss your plan with your pharmacist or doctor.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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The Full Monographs Behind UT Answer’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Vitamin C

Interacts with 207 drugs

Vitamin C (ascorbic acid) is an essential nutrient your body needs but cannot make, so you must get it from food or supplements. It's important for immune function, collagen, and acts as an...

Read the full Vitamin C monograph → Herb & supplement monograph

D-mannose

D-mannose is a natural sugar most often used to help prevent urinary tract infections, especially those caused by E. coli. Early research is promising for prevention, but the evidence is sti...

Read the full D-mannose monograph → Herb & supplement monograph

Caprylic Acid

Interacts with 262 drugs

Caprylic acid is a medium-chain fatty acid found in coconut oil and palm kernel oil that is popularly used for yeast overgrowth and gut health. While laboratory studies show it has antimicro...

Read the full Caprylic Acid monograph → Herb & supplement monograph

Cranberry

Interacts with 712 drugs

Cranberry is best known for helping to prevent repeated urinary tract infections (UTIs) in some people, and the evidence here is moderate but mixed. It is not a reliable treatment for an act...

Read the full Cranberry monograph → Herb & supplement monograph

Uva Ursi

Interacts with 803 drugs

Uva ursi is a traditional herb used mainly for urinary tract infections, and its leaves contain a compound called arbutin that may have antimicrobial effects in the urine. Evidence in people...

Read the full Uva Ursi monograph →
Sources

Sources & How We Checked

UT Answer's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 103 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Vitamin C 51 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Back DJ, Breckenridge AM, MacIver M, et al. Interaction of ethinyloestradiol with ascorbic acid in man. Br Med J (Clin Res Ed) 1981;282:1516.
  3. Morris JC, Beeley L, Ballantine N. Interaction of ethinyloestradiol with ascorbic acid in man [letter]. Br Med J (Clin Res Ed) 1981;283:503.
  4. Labriola D, Livingston R. Possible interactions between dietary antioxidants and chemotherapy. Oncology 1999;13:1003-8.
  5. Dwyer JH, Merz NB, Shirocre AM, et al. Progression of early atherosclerosis and intake of vitamin C and vitamin E from supplements and food. The Los Angeles Atherosclerosis Study. 41st Annual Conference on Cardiovascular Disease Epidemiology and Prevent
  6. Levine M, Rumsey SC, Daruwala R, et al. Criteria and recommendations for vitamin C intake. JAMA 1999;281:1415-23. PubMed
  7. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  8. Segal S, Kaminski S. Drug-nutrient interactions. American Druggist 1996 Jul;42-8.
  9. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press, 2000. Available at: http://www.nap.edu/books/0309069351/html/.
  10. Houston JB, Levy G. Drug biotransformation interactions in man VI: Acetaminophen and ascorbic acid. J Pharm Sci 1976;65:1218-21. PubMed
  11. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med 2001;345:1583-93. DOI
  12. Rosenthal G. Interaction of ascorbic acid and warfarin. JAMA 1971;215:1671. DOI
  13. Hume R, Johnstone JM, Weyers E. Interaction of ascorbic acid and warfarin. JAMA 1972;219:1479. DOI
  14. Smith EC, Skalski RJ, Johnson GC, Rossi GV. Interaction of ascorbic acid and warfarin. JAMA 1972;221:1166. DOI
  15. Traxer O, Huet B, Poindexter J, et al. Effect of ascorbic acid consumption on urinary stone risk factors. J Urol 2003;170:397-401.. PubMed
  16. Domingo JL, Gomez M, Llobet JM, Richart C. Effect of ascorbic acid on gastrointestinal aluminum absorption (letter). Lancet 1991;338:1467.
  17. Domingo JL, Gomez M, Llobet JM, Corbella J. Influence of some dietary constituents on aluminum absorption and retention in rats. Kidney Int 1991;39:598-601. PubMed
  18. Partridge NA, Regnier FE, White JL, Hem SL. Influence of dietary constituents on intestinal absorption of aluminum. Kidney Int 1989;35:1413-7. PubMed
  19. Mc Leod DC, Nahata MC. Inefficacy of ascorbic acid as a urinary acidifier (letter). N Engl J Med 1977;296:1413. DOI
  20. Hansten PD, Hayton WL. Effect of antacid and ascorbic acid on serum salicylate concentration. J Clin Pharmacol 1980;20:326-31. PubMed
  21. Dysken MW, Cumming RJ, Channon RA, Davis JM. Drug interaction between ascorbic acid and fluphenazine. JAMA 1979;241:2008. DOI
  22. Vihtamaki T, Parantainen J, Koivisto AM, et al. Oral ascorbic acid increases plasma oestradiol during postmenopausal hormone replacement therapy. Maturitas 2002;42:129-35. PubMed
  23. Slain D, Amsden JR, Khakoo RA, et al. Effect of high-dose vitamin C on the steady-state pharmacokinetics of the protease inhibitor indinavir in healthy volunteers. Pharmacotherapy 2005;25:165-70. PubMed
  24. Cheung MC, Zhao XQ, Chait A, et al. Antioxidant supplements block the response of HDL to simvastatin-niacin therapy in patients with coronary artery disease and low HDL. Arterioscler Thromb Vasc Biol 2001;21:1320-6. PubMed
  25. Feetam CL, Leach RH, Meynell MJ. Lack of a clinically important interaction between warfarin and ascorbic acid. Toxicol Appl Pharmacol 1975;31:544-7. PubMed
  26. Weintraub M, Griner PF. Warfarin and ascorbic acid: lack of evidence for a drug interaction. Toxicol Appl Pharmacol 1974;28:53-6. PubMed
  27. Lee DH, Folsom AR, Harnack L, et al. Does supplemental vitamin C increase cardiovascular disease risk in women with diabetes? Am J Clin Nutr 2004;80:1194-200. PubMed
  28. Taylor EN, Stampfer MJ, Curhan GC. Dietary factors and the risk of incident kidney stones in men: new insights after 14 years of follow-up. J Am Soc Nephrol 2004;15:3225-32. PubMed
  29. Ward NC, Hodgson JM, Croft KD, et al. The combination of vitamin C and grape-seed polyphenols increases blood pressure: a randomized, double-blind, placebo-controlled trial. J Hypertens 2005;23:427-34.. PubMed
  30. Prasad KN. Rationale for using high-dose multiple dietary antioxidants as an adjunct to radiation therapy and chemotherapy. J Nutr 2004;134:3182S-3S. PubMed
  31. Conklin KA. Cancer chemotherapy and antioxidants. J Nutr 2004;134:3201S-3204S. PubMed
  32. Fairweather-Tait S, Hickson K, McGaw B, et al. Orange juice enhances aluminium absorption from antacid preparation. Eur J Clin Nutr. 1994;48(1):71-3.
  33. Gruenwald, J., Graubaum, H. J., Busch, R., and Bentley, C. Safety and tolerance of ester-C compared with regular ascorbic acid. Adv.Ther. 2006;23(1):171-178.
  34. Rahimi, R., Nikfar, S., Rezaie, A., and Abdollahi, M. A meta-analysis on the efficacy and safety of combined vitamin C and E supplementation in preeclamptic women. Hypertens.Pregnancy. 2009;28(4):417-434. PubMed
  35. Einerson, B., Nathorn, C., Kitiyakara, C., Sirada, M., and Thamlikitkul, V. The efficacy of ascorbic acid in suboptimal responsive anemic hemodialysis patients receiving erythropoietin: a meta-analysis. J Med.Assoc.Thai. 2011;94 Suppl 1:S134-S146.
  36. Li, G., Li, L., Yu, C., and Chen, L. Effect of vitamins C and E supplementation on Helicobacter pylori eradication: a meta-analysis. Br.J Nutr 2011;106(11):1632-1637.
  37. Chen X, Shen L, Gu X, et al. High-dose supplementation with vitamin C--induced pediatric urolithiasis: the first case report in a child and literature review. Urology. 2014;84(4):922-4. PubMed
  38. Sattar A, Willman JE, Kolluri R. Possible warfarin resistance due to interaction with ascorbic acid: case report and literature review. Am J Health Syst Pharm. 2013;70(9):782-6. PubMed
  39. Yaich S, Chaabouni Y, Charfeddine K, et al. Secondary oxalosis due to excess vitamin C intake: a cause of graft loss in a renal transplant recipient. Saudi J Kidney Dis Transpl. 2014;25(1):113-6. PubMed
  40. Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
  41. Rumbold A, Ota E, Nagata C, Shahrook S, Crowther CA. Vitamin C supplementation in pregnancy. Cochrane Database Syst Rev. 2015;(9):CD004072. PubMed
  42. Seo MS, Kim JK, Shim JY. High-dose vitamin C promotes regression of multiple pulmonary metastases originating from hepatocellular carcinoma. Yonsei Med J. 2015;56(5):1449-52. PubMed
  43. Skelin M, Lucijanic T, Amidzic Klaric D, et al. Factors Affecting Gastrointestinal Absorption of Levothyroxine: A Review. Clin Ther. 2017 Feb;39(2):378-403. PubMed
  44. Jiang K, Tang K, Liu H, Xu H, Ye Z, Chen Z. Ascorbic acid supplements and kidney stones incidence among men and women: a systematic review and meta-analysis. Urol J. 2019;16(2):115-120.
  45. Thomas S, Patel D, Bittel B, et al. Effect of High-Dose Zinc and Ascorbic Acid Supplementation vs Usual Care on Symptom Length and Reduction Among Ambulatory Patients With SARS-CoV-2 Infection: The COVID A to Z Randomized Clinical Trial. JAMA Netw Open. 2 PubMed
  46. Giffen MA, McLemore JL. Hyperoxalosis Secondary to Intravenous Vitamin C Administration as a Non-Allopathic Treatment for Cancer. Acad Forensic Pathol 2019;9(1-2):118-126. PubMed
  47. Maike A, Sturgill D, Gallan A. Oxalate Nephropathy in a Renal Transplant Recipient After Receiving High Dose Ascorbic Acid. Am J Med Sci 2021. PubMed
  48. Shen ZY, Chen YR, Wang MC, Chang SS. High-dose vitamin C-induced acute oxalate nephropathy in a renal transplant recipient: a case report and literature review. Asian J Surg 2022. PubMed
  49. Yanase F, Spano S, Maeda A, et al. Mega-dose sodium ascorbate: a pilot, single-dose, physiological effect, double-blind, randomized, controlled trial. Crit Care 2023;27(1):371. PubMed
  50. Sharma Y, Sumanadasa S, Shahi R, et al. Efficacy and safety of vitamin C supplementation in the treatment of community-acquired pneumonia: a systematic review and meta-analysis with trial sequential analysis. Sci Rep 2024;14(1):11846. PubMed
  51. Pejcic AV, Petrovic NZ, Djordjic MD, Milosavljevic MN. Vitamin C Levels in Pregnant Women and the Efficacy of Vitamin C Supplements in Preventing Premature Rupture of Membranes: A Systematic Review and Meta-Analysis. Balkan Med J 2024;41(4):248-260. PubMed

See these in context on the Vitamin C monograph →

D-mannose 6 references
  1. Westphal V, Kjaergaard S, Davis JA, et al. Genetic and metabolic analysis of the first adult with congenital disorder of glycosylation type Ib: long-term outcome and effects of mannose supplementation. Mol Genet Metab 2001;73:77-85. PubMed
  2. Kranjcec B, Papes D, Altarac S. D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World J Urol. 2014 Feb;32(1):79-84.
  3. de Lonlay P, Seta N. The clinical spectrum of phosphomannose isomerase deficiency, with an evaluation of mannose treatment for CDG-Ib. Biochim Biophys Acta. 2009;1792(9):841-3. PubMed
  4. Harms HK, Zimmer KP, Kurnik K, Bertele-Harms RM, Weidinger S, Reiter K. Oral mannose therapy persistently corrects the severe clinical symptoms and biochemical abnormalities of phosphomannose isomerase deficiency. Acta Paediatr. 2002;91(10):1065-72. DOI
  5. . Damen G, de Klerk H, Huijmans J, den Hollander J, Sinaasappel M. Gastrointestinal and other clinical manifestations in 17 children with congenital disorders of glycosylation type Ia, Ib, and Ic. J Pediatr Gastroenterol Nutr. 2004;38(3):282-7. DOI
  6. Lenger SM, Bradley MS, Thomas DA, Bertolet MH, Lowder JL, Sutcliffe S. D-mannose vs other agents for recurrent urinary tract infection prevention in adult women: a systematic review and meta-analysis. Am J Obstet Gynecol. 2020;223(2):265.e1-265.e13. PubMed

See these in context on the D-mannose monograph →

Caprylic Acid 5 references
  1. Massolini G, Aubry AF, McGann A, Wainer IW. Determination of the magnitude and enantioselectivity of ligand binding to rat and rabbit serum albumins using immobilized-protein high performance liquid chromatography stationary phases. Biochem Pharmacol 1993 PubMed
  2. Kristev A, Mitkov D, Lukanov Y, Chapkynov P. The effect of octanoic fatty acid on the cardiovascular system of the guinea pig. Cor Vasa 1989;31(4):321-7.
  3. Hayball PF, Holman JW, Nation RL. Influence of octanoic acid on the reversible protein binding of ketorolac enantiomers to human serum albumin (HSA): comparative liquid chromatographic studies using a HSA chiral stationary phase. J Chromatogr B Biomed App PubMed
  4. Noctor TA, Wainer IW, Hage DS. Allosteric and competitive displacement of drugs from human serum albumin by octanoic acid, as revealed by high-performance liquid affinity chromatography, on a human serum albumin-based stationary phase. J Chromatogr 1992;5 PubMed
  5. Voller B, Lines E, McCrossin G, et al. Dose-escalation study of octanoic acid in patients with essential tremor. J Clin Invest. 2016;126(4):1451-7. PubMed

See these in context on the Caprylic Acid monograph →

Cranberry 33 references
  1. Anon. Possible interaction between warfarin and cranberry juice. Current Problems in Pharmacovigilance 2003;29:8. PubMed
  2. Greenblatt DJ, von Moltke LL, Perloff ES, et al. Interaction of flurbiprofen with cranberry juice, grape juice, tea, and fluconazole: in vitro and clinical studies. Clin Pharmacol Ther 2006;79:125-33. PubMed
  3. Hodek P, Trefil P, Stiborova M. Flavonoids-potent and versatile biologically active compounds interacting with cytochromes P450. Chem Biol Interact 2002;139:1-21.. PubMed
  4. Grant P. Warfarin and cranberry juice: An interaction? J Heart Valve Dis 2004;13:25-6.
  5. Suvarna R, Pirmohamed M, Henderson L. Possible interaction between warfarin and cranberry juice. BMJ 2003;327:1454. PubMed
  6. Li Z, Seeram NP, Carpenter CL, et al. Cranberry does not affect prothrombin time in male subjects on warfarin. J Am Diet Assoc 2006;106:2057-61. PubMed
  7. Lilja JJ, Backman JT, Neuvonen PJ. Effects of daily ingestion of cranberry juice on the pharmacokinetics of warfarin, tizanidine, and midazolam - probes of CYP2C9, CYP1A2 and CYP3A4. Clin Pharmacol The 2007:81:833-9. PubMed
  8. Wing DA, Rumney PJ, Preslicka CW, Chung JH. Daily cranberry juice for the prevention of asymptomatic bacteriuria in pregnancy: a randomized, controlled pilot study. J Urol 2008;180:1367-72. PubMed
  9. Mohammed Abdul MI, Jiang X, Williams KM, et al. Pharmacodynamic interaction of warfarin with cranberry but not with garlic in healthy subjects. Br J Pharmacol 2008;154:1691-700. PubMed
  10. McMurdo MET, Argo I, Phillips G, et al. Cranberry or trimethoprim for the prevention of recurrently urinary tract infections? A randomized controlled trial in older women. J Antimicrob Chemother 2009;63:389-95.
  11. Mergenhagen KA, Sherman O. Elevated International Normalized Ratio after concurrent ingestion of cranberry sauce and warfarin. Am J Health-Syst Pharm 2008;65:2113-6. PubMed
  12. Ansell J, McDonough M, Zhao Y, et al. The absence of an interaction between warfarin and cranberry juice: a randomized, double-blind trial. J Clin Pharmacol 2009;49:824-30. PubMed
  13. Haber SL, Cauthon KA, Raney EC. Cranberry and warfarin interaction: a case report and review of the literature. Consult Pharm 2012;27:58-65. PubMed
  14. Hamann GL, Campbell JD, George CM. Warfarin-cranberry juice interaction. Ann Pharmacother 2011;45:e17. PubMed
  15. Roberts D, Flanagan P. Case report: Cranberry juice and warfarin. Home Healthc Nurse 2011;29:92-7.
  16. Garcia-Calatayud, S., Larreina Cordoba, J. J., and Lozano De La Torre MJ. [Severe cranberry juice poisoning]. An.Esp.Pediatr. 2002;56(1):72-73.
  17. Patel, D. A., Gillespie, B., Sobel, J. D., Leaman, D., Nyirjesy, P., Weitz, M. V., and Foxman, B. Risk factors for recurrent vulvovaginal candidiasis in women receiving maintenance antifungal therapy: results of a prospective cohort study. Am J Obstet.Gy PubMed
  18. Isele, H. [Fatal bleeding under warfarin plus cranberry juice. Is it due to salicylic acid?]. MMW.Fortschr.Med 3-11-2004;146(11):13.
  19. Linsenmeyer, T. A., Harrison, B., Oakley, A., Kirshblum, S., Stock, J. A., and Millis, S. R. Evaluation of cranberry supplement for reduction of urinary tract infections in individuals with neurogenic bladders secondary to spinal cord injury. A prospecti
  20. McMurdo, M. E., Bissett, L. Y., Price, R. J., Phillips, G., and Crombie, I. K. Does ingestion of cranberry juice reduce symptomatic urinary tract infections in older people in hospital? A double-blind, placebo-controlled trial. Age Ageing 2005;34(3):256- PubMed
  21. Sylvan, L. and Justice, N. P. Possible interaction between warfarin and cranberry juice. Am Fam.Physician 9-15-2005;72(6):1000.
  22. Niklasson, A. and Andren, L. [Interaction between Waran and cranberry juice]. Lakartidningen 3-15-2006;103(11):853-854.
  23. Rindone, J. P. and Murphy, T. W. Warfarin-cranberry juice interaction resulting in profound hypoprothrombinemia and bleeding. Am J Ther 2006;13(3):283-284. PubMed
  24. Uesawa, Y. and Mohri, K. Effects of cranberry juice on nifedipine pharmacokinetics in rats. J Pharm Pharmacol 2006;58(8):1067-1072. PubMed
  25. Valentova, K., Stejskal, D., Bednar, P., Vostalova, J., Cihalik, C., Vecerova, R., Koukalova, D., Kolar, M., Reichenbach, R., Sknouril, L., Ulrichova, J., and Simanek, V. Biosafety, antioxidant status, and metabolites in urine after consumption of dried
  26. Royer, D. J., George, J. N., and Terrell, D. R. Thrombocytopenia as an adverse effect of complementary and alternative medicines, herbal remedies, nutritional supplements, foods, and beverages. Eur J Haematol 2010;84(5):421-429. PubMed
  27. Stapleton, A. E., Dziura, J., Hooton, T. M., Cox, M. E., Yarova-Yarovaya, Y., Chen, S., and Gupta, K. Recurrent urinary tract infection and urinary Escherichia coli in women ingesting cranberry juice daily: a randomized controlled trial. Mayo.Clin.Proc. PubMed
  28. Doad GJ, Kabange W. Cranberry juice, atorvastatin and back pain. J Med Assoc Ga 2014;103(1):14.
  29. Griffiths AP, Beddall A, Pegler S. Fatal haemopericardium and gastrointestinal haemorrhage due to possible interaction of cranberry juice with warfarin. J R Soc Promot Health 2008;128(6):324-6. PubMed
  30. Mellen CK, Ford M, Rindone JP. Effect of high-dose cranberry juice on the pharmacodynamics of warfarin in patients. Br J Clin Pharmacol 2010;70(1):139-42. PubMed
  31. Ushijima K, Tsuruoka S, Tsuda H, Hasegawa G, Obi Y, Kaneda T, Takahashi M, Maekawa T, Sasaki T, Koshimizu TA, Fujimura A. Cranberry juice suppressed the diclofenac metabolism by human liver microsomes, but not in healthy human subjects. Br J Clin Pharmaco PubMed
  32. Ngo N, Brantley SJ, Carrizosa DR, et al. The warfarin-cranberry juice interaction revisited: A systematic in vitro-in vivo evaluation. J Exp Pharmacol. 2010;2010(2):83-91.
  33. Williams G, Stothart CI, Hahn D, Stephens JH, Craig JC, Hodson EM. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev 2023;11(11):CD001321. PubMed

See these in context on the Cranberry monograph →

Uva Ursi 8 references
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. Terry C. Telger, transl. 3rd ed. Berlin, GER: Springer, 1998.
  3. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  4. Wang L, Del Priore LV. Bull's-eye maculopathy secondary to herbal toxicity from uva ursi. Am J Ophthalmol 2004;137:1135-7. PubMed
  5. Beaux, D., Fleurentin, J., and Mortier, F. Effect of extracts of Orthosiphon stamineus Benth, Hieracium pilosella L., Sambucus nigra L. and Arctostaphylos uva-ursi (L.) Spreng. in rats. Phytother.Res 1999;13(3):222-225.
  6. de Arriba SG, Naser B, Nolte KU. Risk assessment of free hydroquinone derived from Arctostaphylos Uva-ursi folium herbal preparations. Int J Toxicol. 2013;32(6):442-453.
  7. Park JB, Kim D, Min JS, et al. Identification and characterization of in vitro inhibitors against UDP-glucuronosyltransferase 1A1 in uva-ursi extracts and evaluation of in vivo uva-ursi-drug interactions. Food Chem Toxicol. 2018;120:651-661. PubMed
  8. Chauhan B, Yu C, Krantis A, et al. In vitro activity of uva-ursi against cytochrome P450 isoenzymes and P-glycoprotein. Can J Physiol Pharmacol. 2007;85(11):1099-107.

See these in context on the Uva Ursi monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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