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Dietary supplement

Ultra-C 2000 mg Sustained Release Ingredients & Drug Interactions

by NaturesPlus

Ultra-C 2000 mg Sustained Release label
See full label image
Tablet Or Pill 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 Ultra-C 2000 mg Sustained Release 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

Ultra-C 2000 mg Sustained Release is a dietary supplement by NaturesPlus with 2 active ingredients. Its ingredients are commonly taken for common cold and immune support, antioxidant support, skin health and collagen formation.Based on those ingredients, 290 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Rose Hip, Vitamin C. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Ultra-C 2000 mg Sustained Release by NaturesPlus

Ask about any prescription or over-the-counter medication and we check it for interactions with Ultra-C 2000 mg Sustained Release by NaturesPlus — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Ultra-C 2000 mg Sustained Release by NaturesPlus

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 2 of its 2 active ingredients.
  • No proprietary blends here — you can verify the dose of every single component.

This product has 2 active ingredients: vitamin C and rose hip. The vitamin C provides 2000 mg per dose in a sustained-release form, so it's released gradually over time.

Rose hip is added as a natural source of additional vitamin C and other plant compounds. The rest of the tablet is made up of inactive ingredients—stearic acid, microcrystalline cellulose, silica, magnesium stearate, carob, hydroxypropylmethylcellulose, and pharmaceutical glaze—which help form and protect the tablet.

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: immune support and antioxidant defense.
  • We looked for evidence on: Common cold, Influenza, Exercise-induced respiratory infections, Acute bronchitis, Coronavirus disease 2019 (COVID-19), HIV/AIDS — and 4 related terms.
  • The strongest evidence on file: Vitamin C is rated "Possibly Effective" for Exercise-induced respiratory infections (Natural Medicines).
  • Also on file: Vitamin C is rated "Possibly Ineffective" for Acute bronchitis, Fractures.
  • Also on file: Vitamin C is rated "Likely Ineffective" for Coronavirus disease 2019 (COVID-19).

Vitamin C is effective for preventing and treating vitamin C deficiency. It's possibly effective for anemia of chronic disease, atrial fibrillation, cataracts, and preventing respiratory infections triggered by exercise.

Rose hip is possibly effective for postoperative pain and osteoarthritis, though we don't have enough reliable evidence to rate it for high cholesterol. The evidence supporting these uses comes from clinical trials, but for several conditions the data is still developing.

The evidence, ingredient by ingredient Vitamin C Rose Hip

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 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin C from food and normal supplement doses is generally well tolerated. However, very high doses—above 2 grams daily—can cause abdominal cramps, heartburn, diarrhea, nausea, vomiting, and headache.

In people prone to kidney stones, high doses have been reported to trigger them. Rose hip is generally well tolerated as a food or food-based supplement, though some people report flatulence, loose stools, headache, or vertigo.

Most gastrointestinal side effects in studies occurred at the same rate as placebo. For pregnancy and breastfeeding, normal amounts of vitamin C from food and prenatal vitamins are considered likely safe, but the safety data advises against high-dose supplements unless your doctor recommends them.

Rose hip has insufficient data on file to advise either way in pregnancy or breastfeeding—talk with your doctor or pharmacist for personalized guidance.

Side effects, ingredient by ingredient Vitamin C Rose Hip

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?
  • 2 of the 2 matched ingredients can interact with medications — Rose Hip, Vitamin C.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; cancer treatments; lithium.
  • For scale: 290 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.

Before taking Ultra-C 2000 mg, double-check with your pharmacist if you take oral contraceptives or hormone replacement therapy (estrogens can be increased), blood thinners like warfarin or anticoagulant/antiplatelet drugs (effectiveness may be reduced), thyroid medication such as levothyroxine (absorption may increase), chemotherapy drugs including alkylating agents and antitumor antibiotics (their activity might be blurred), or lithium (levels could rise). Moderate severity interactions are documented with all of these drug types.

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.

This is a straightforward vitamin C supplement with rose hip added. If you take birth control, blood thinners, thyroid medication, HIV drugs, or chemotherapy, you need to check your specific medications with the tool on this page before starting.

Anyone with a history of kidney stones should use caution with high-dose vitamin C. For most other people, this product is generally well tolerated at the stated dose.

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

Assessment coverage: 2 of 2 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Oct 24, 2023.

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 Ultra-C 2000 mg Sustained Release, straight from the product label.

Brand NaturesPlus
Barcode (UPC) 097467022201
Net contents 60 Tablet(s)
Market status On market
Date entered into DSLD Oct 24, 2023
DSLD ID 298623
Product type Botanical With Nutrients
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Vegetarian, Adult (18 - 50 Years), No Allergies, 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 Ultra-C 2000 mg Sustained Release by NaturesPlus, 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:
1 Tablet(s)
Maximum serving Sizes:
1 Tablet(s)
Servings per container
60
UPC/BARCODE
097467022201
IngredientAmount% DV
Vitamin C2000 mg2222%
Rose Hip200 mg--

Other ingredients: Stearic Acid, Microcrystalline Cellulose, Silica, Magnesium Stearate, Carob, Hydroxypropylmethylcellulose, Pharmaceutical Glaze

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.
Formula

Vitamin C is an antioxidant involved in over three hundred metabolic functions in the body. It is an essential vitamin, providing nutritional support for Free-Radical Defense and is vitally important to support the immune system's ability to protect our bodies. In a special base which provides for the gradual release of high potency vitamin C over a prolonged period of time.

Formulation

Free from artificial colors and artificial preservatives. Free from all of the major allergens identified in the U.S. Food Allergen Labeling and Consumer Protection Act.

Vegetarian

Gluten Free

Micro-Gel sustained release system

Maximum Potency

Immune Support

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.

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

Directions: One tablet daily.

Storage

Keep tightly closed in a cool, dry place.

Precautions

Keep out of reach of children.

Brand IP Statement(s)

Copyright Natural Organics

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

See for yourself

Ultra-C 2000 mg Sustained Release by NaturesPlus label

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

Ultra-C 2000 mg Sustained Release 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 Ultra-C 2000 mg Sustained Release by NaturesPlus

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Tablet(s) Dosage formTablet Or Pill Servings per container60 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.

Vitamin C

Interacts with
207 drugs
2000 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

Rose Hip

Interacts with
213 drugs
200 mg per serving Form: Rosa canina

Rose hip is the vitamin C–rich fruit of the wild rose, used traditionally for colds and joint pain. A standardized rose hip powder has some research s...

Rose Hip monograph & interactions

Other (inactive) ingredients: Stearic Acid, Microcrystalline Cellulose, Silica, Magnesium Stearate, Carob, Hydroxypropylmethylcellulose, Pharmaceutical Glaze. These complete the product’s ingredient list but are not active constituents.

Interaction report

Ultra-C 2000 mg Sustained Release by NaturesPlus Drug Interactions

Want to check YOUR meds against Ultra-C 2000 mg Sustained Release?

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
290Drugs
218 Moderate 72 Minor

Ingredients driving the most interactions

Rose Hip 213
Vitamin C 207

Individual Drug Interactions

The ingredients in Ultra-C 2000 mg Sustained Release interact with 290 drugs. Click any drug to see the details.

2 of the 2 ingredients in Ultra-C 2000 mg Sustained Release interact with drugs. Each result below shows which ingredient is responsible. Rose Hip Vitamin C

Each ingredient & the kinds of drugs it affects

For each ingredient in Ultra-C 2000 mg Sustained Release 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.

Rose Hip8 drug types · 213 drugs

Alkylating Agents

Theoretically, the antioxidant effects of rose hip might reduce the effectiveness of alkylating agents but might also reduce the oxidative damage caused by certain alkylating agents.
Rose hip contains vitamin C. 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. Further, some animal research suggests that the antioxidant effects of rose hip might attenuate cyclophosphamide-induced testicular toxicity. More evidence is needed to determine what effect, if any, antioxidants found in rose hip, such as vitamin C, have on the effectiveness and adverse effects of chemotherapy.

Likelihood Possible Evidence D
Aluminum

Theoretically, rose hip might increase the amount of aluminum absorbed from aluminum compounds.
Rose hip contains vitamin C. Theoretically, vitamin C increases the absorption of aluminum. Concomitant use might increase aluminum absorption, but the clinical significance of this is unknown. Administer rose hip two hours before or four hours after antacids.

Likelihood Probable Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, rose hip might reduce the effectiveness of anticoagulant or antiplatelet drugs.
In vitro and animal research suggests that a constituent of rose hip, rugosin E, can induce platelet aggregation. This has not been shown in humans. Theoretically, concomitant use of rose hip might reduce the effectiveness of antiplatelet or anticoagulant drugs.

Likelihood Possible Evidence D
Antitumor Antibiotics

Theoretically, the antioxidant effects of rose hip might reduce the effectiveness of antitumor antibiotics.
Rose hip contains the antioxidant vitamin C. There is concern that antioxidants might reduce the activity of chemotherapy drugs that generate free radicals, such as antitumor antibiotics. In contrast, other researchers theorize that antioxidants might make antitumor antibiotic 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 antitumor antibiotic chemotherapy.

Likelihood Possible Evidence D
Estrogens

Theoretically, rose hip might increase blood levels of estrogens.
Rose hip contains vitamin C. Increases in plasma estrogen levels of up to 55% have occured 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. However, increases in plasma estrogen levels may occur when women who are deficient in vitamin C take supplements.

Likelihood Possible Evidence D
Lithium

Theoretically, rose hip might increase blood levels of lithium.
Rose hip is thought to have diuretic properties. Theoretically, due to these potential diuretic effects, rose hip might reduce excretion and increase levels of lithium. The dose of lithium might need to be decreased.

Likelihood Probable Evidence D
Aspirin

Theoretically, rose hip might reduce the clearance of aspirin; however, its vitamin C content is likely too low to produce clinically significant effects.
Rose hip contains vitamin C. It has been suggested that acidification of the urine by vitamin C can decrease the urinary excretion of salicylates, increasing 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. The vitamin C content of rose hip is typically about 500 mg per 100 grams. Thus, a clinically significant interaction between rose hip and aspirin is unlikely.

Likelihood Unlikely Evidence B
Warfarin (Coumadin)

Theoretically, rose hip might reduce the effectiveness of warfarin; however, its vitamin C content is likely too low to produce clinically significant effects.
Rose hip contains vitamin C. High doses of vitamin C may reduce the response to warfarin, possibly by causing diarrhea and reducing warfarin absorption. This occurred in two people who took up to 16 grams daily of vitamin C, and resulted in decreased prothrombin time. Lower doses of 5-10 grams daily of vitamin C can also reduce warfarin absorption, but this does not seem to be clinically significant. The vitamin C content of rose hip is typically about 500 mg per 100 grams. Thus, a clinically significant interaction between rose hip and warfarin is unlikely.

Likelihood Unlikely Evidence D
Rose Hip 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 Ultra-C 2000 mg Sustained Release, from the product label.

NaturesPlus

See all NaturesPlus products
Name
Natural Organics Laboratories, Inc. makers of Nature's Plus
Street Address
9500 New Horizons Blvd.
City
Amityville
State
New York
ZipCode
11701
Web Address
www.naturesplus.com
Pharmacist Counseling Corner

Ultra-C 2000 mg Sustained Release by NaturesPlus: Common Questions

Does Ultra-C 2000 mg Sustained Release by NaturesPlus interact with any medications?
Yes. Based on its ingredients, Ultra-C 2000 mg Sustained Release has a known interaction with 290 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Ultra-C 2000 mg Sustained Release contains 2 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 interfere with my birth control?
Yes, it's a real concern. Vitamin C at high doses can raise estrogen blood levels by up to 55%, and this product delivers 2000 mg. That's enough to potentially affect how well your birth control or HRT works. Check with your pharmacist before you start, especially if your hormonal contraceptive is already not working well for you.
What are the most common side effects?
At this dose, vitamin C commonly causes abdominal cramps, heartburn, diarrhea, nausea, and headache—most often if you're sensitive to high doses. Rose hip may add flatulence or loose stools. These effects are more likely above 2 grams of vitamin C daily, so you're at the upper edge here.
Can I take this if I'm pregnant?
Normal amounts of vitamin C from food and prenatal vitamins are considered safe in pregnancy. However, the safety data advises against high-dose supplements unless your doctor specifically recommends them. Since this product delivers 2000 mg, talk with your doctor or pharmacist to see if it's right for you.
Is this product just vitamin C, or is rose hip adding something different?
Rose hip is included because it naturally contains vitamin C and other plant compounds. It's not a separate active ingredient with its own proven benefits at supplement doses—rose hip itself is possibly effective for postoperative pain and osteoarthritis, but the evidence is still developing. Most of the action here comes from the vitamin C.
What does 'sustained release' mean?
It means the tablet releases the vitamin C slowly over time instead of all at once. This can be easier on your stomach and keeps levels more steady throughout the day, but it doesn't change how it interacts with your medications.
I have kidney stones. Is this safe for me?
High-dose vitamin C has been reported to trigger kidney stones in people prone to them. At 2000 mg daily, this product is a high dose, so talk with your doctor before taking it if you have a history of kidney stones.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Ultra-C 2000 mg Sustained Release label
Go deeper

The Full Monographs Behind Ultra-C 2000 mg Sustained Release’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

Rose Hip

Interacts with 213 drugs

Rose hip is the vitamin C–rich fruit of the wild rose, used traditionally for colds and joint pain. A standardized rose hip powder has some research support for easing osteoarthritis symptom...

Read the full Rose Hip monograph →
Sources

Sources & How We Checked

Ultra-C 2000 mg Sustained Release'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 75 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
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See these in context on the Vitamin C monograph →

Rose Hip 24 references
  1. Foster S, Tyler VE. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 3rd ed., Binghamton, NY: Haworth Herbal Press, 1993.
  2. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
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  7. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  8. 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/.
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  12. Mc Leod DC, Nahata MC. Inefficacy of ascorbic acid as a urinary acidifier (letter). N Engl J Med 1977;296:1413. DOI
  13. Hansten PD, Hayton WL. Effect of antacid and ascorbic acid on serum salicylate concentration. J Clin Pharmacol 1980;20:326-31. PubMed
  14. 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
  15. 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
  16. Weintraub M, Griner PF. Warfarin and ascorbic acid: lack of evidence for a drug interaction. Toxicol Appl Pharmacol 1974;28:53-6. PubMed
  17. 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
  18. Conklin KA. Cancer chemotherapy and antioxidants. J Nutr 2004;134:3201S-3204S. PubMed
  19. Andersson U, Berger K, Hogberg A, et al. Effects of rose hip intake on risk markers of type 2 diabetes and cardiovascular disease: a randomized, double-blind, cross-over investigation in obese persons. Eur J Clin Nutr 2012;66:585-90. PubMed
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  21. Winther, K., Apel, K., and Thamsborg, G. A powder made from seeds and shells of a rose-hip subspecies (Rosa canina) reduces symptoms of knee and hip osteoarthritis: a randomized, double-blind, placebo-controlled clinical trial. Scand J Rheumatol. 2005;34
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  24. Parandin R, Ghowsi M, Dadbod A. Protective effects of hydroalcoholic extract of Rosa canina L. fruit on cyclophosphamide-induced testicular toxicity in mice. Avicenna J Phytomed 2023;13(1):7-17.

See these in context on the Rose Hip 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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