Interactions on record — worth a quick check against your medications. Based on 2 of 3 ingredients. Check your meds →
Dietary supplement

Collagen Protein Unflavored Ingredients & Drug Interactions

by Bulletproof

Collagen Protein Unflavored label
See full label image
Powder Category: Amino Acid/protein
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 Collagen Protein Unflavored 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

Collagen Protein Unflavored is a dietary supplement by Bulletproof with 3 active ingredients. Its ingredients are commonly taken for common cold and immune support, antioxidant support, skin health and collagen formation.Based on those ingredients, 207 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are 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 Collagen Protein Unflavored by Bulletproof

Ask about any prescription or over-the-counter medication and we check it for interactions with Collagen Protein Unflavored by Bulletproof — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Collagen Protein Unflavored by Bulletproof

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 12, 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.

Bulletproof Collagen Protein Unflavored contains 2 active ingredients: vitamin C and hydrolyzed collagen. Vitamin C is included for its antioxidant role and its established role in immune and collagen support.

Hydrolyzed collagen—also called collagen peptides—is a protein broken down into smaller, more easily absorbed pieces; it's the main protein base of this supplement. There are no inactive ingredients (fillers or binders) listed in this product.

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: skin, bone and joint support.
  • We looked for evidence on: Aging skin, Atrophic acne scars, Brittle nails, Cellulite, Dry skin, Exercise-induced muscle damage — and 4 related terms.
  • The strongest evidence on file: Collagen Peptides is rated "Possibly Effective" for Aging skin (Natural Medicines).
  • Also on file: Collagen Peptides is rated "Possibly Effective" for Dry skin.
  • Also on file: Vitamin C is rated "Possibly Ineffective" for Fractures.

Vitamin C is effective for preventing or treating vitamin C deficiency and possibly effective for anemia of chronic disease, atrial fibrillation, cataracts, and exercise-induced respiratory infections, based on the evidence we hold. Hydrolyzed collagen is possibly effective for aging skin and dry skin, and possibly ineffective for muscle strength.

The evidence for acne and athletic performance is insufficient to rate. If you're considering this product for a specific goal, check whether the ingredient and the condition match what's been studied.

The evidence, ingredient by ingredient Vitamin C Collagen Peptides

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

People prone to kidney stones should be cautious, as kidney stones have been reported at high doses. Rare serious side effects from very high-dose intravenous vitamin C include kidney damage and elevated sodium levels.

Hydrolyzed collagen is generally well tolerated as a dietary protein. Mild and uncommon side effects may include nausea, indigestion, diarrhea, and gas.

Vitamin C is considered likely safe in normal amounts during pregnancy and lactation (including from food and prenatal vitamins), but high-dose supplements should be avoided unless your doctor directs otherwise. Hydrolyzed collagen has not been well studied in pregnancy or breastfeeding; check with your doctor before using if you are pregnant or nursing.

Side effects, ingredient by ingredient Vitamin C Collagen Peptides

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?
  • 1 of the 2 matched ingredients can interact with medications — Vitamin C.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; cancer treatments.
  • For scale: 207 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 you start Bulletproof Collagen Protein Unflavored, double-check these medication types with your pharmacist: estrogens (including oral contraceptives and hormone replacement therapy), because vitamin C may raise estrogen blood levels; warfarin and other blood thinners, because high-dose vitamin C can reduce their effectiveness; levothyroxine and other thyroid medications; chemotherapy drugs (both alkylating agents and antitumor antibiotics), because vitamin C might reduce their activity; indinavir and other antiretrovirals; and fluphenazine or other antipsychotics. Also mention if you take aluminum-containing compounds or have a history of kidney stones.

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 product may be useful if you want collagen protein and vitamin C support, but vitamin C carries documented interactions with several common medications, especially birth control, hormone therapy, warfarin, thyroid medication, and some chemotherapy drugs. If you take any prescription medication, check your exact drugs with the tool on this page before starting.

Talk to your pharmacist about whether this product fits your personal health picture.

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 Apr 22, 2021.

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 Collagen Protein Unflavored, straight from the product label.

Brand Bulletproof
Barcode (UPC) 815709024253
Net contents 14.3 oz; 405 Gram(s)
Market status On market
Date entered into DSLD Apr 22, 2021
DSLD ID 247875
Product type Amino Acid/protein
Supplement form Powder
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
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 Collagen Protein Unflavored by Bulletproof, 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:
20 Gram(s)
Maximum serving Sizes:
20 Gram(s)
Servings per container
20
UPC/BARCODE
815709024253
IngredientAmount% DV
Calories70 Calorie(s)--
Vitamin C80 mg89%
Protein18 Gram(s)--
Hydrolyzed Collagen20 Gram(s)--

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.
Formulation

Rebuild. Repair. Restore. You ask a lot of your self. Here's what you need to get the job done: Amino acids to support healthy skin, flexible joints, strong bones, and muscles.

Why Bulletproof Collagen Joint & Bone Support Glowing & Hydrated Skin Sustained Energy Mixes Easily in hot or cold drinks Amazing, grazing cows. Bulletproof Collagen Protein comes from cows that spend most of their lives in pasture eating grass.

Supports healthy skin, bones & joints

Collagen protein does not count toward the FDA recommended Percent Daily Value of protein because it lacks one essential amino acid: Tryptophan.

Product of Brazil.

Keep out of reach of children.

Suggested/Recommended/Usage/Directions

Stir up a glass before the gym, after the gym, instead of the gym-hey, it's up to you.

Directions Mix 2 scoops into at least 6 ounces of water, a smoothie, Bulletproof Coffee or your favorite beverage.

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.

Formula

Keto Friendly

20 g Collagen

FDA Statement of Identity

Dietary Supplement

General Statements

Bulletproof is an integrated approach to mind-body nutrition that helps transform the way you feel. Unleash your limitless potential.

Typical Amino Acid Profile (per 20g serving) Alanine 1,800 mg Arginine 1,587 mg Aspartic acid 1,127 mg Glutamic acid 1,933 mg Glycine 4,740 mg Histidine 153 mg Hydroxyproline 2,280 mg Isoleucine 304 mg Leucine 580 mg Lysine 760 mg Methionine 172 mg Phenylalanine 378 mg Proline 2,720 mg Serine 638 mg Threonine 386 mg Tryptophan 0 mg Tyrosine 113 mg Valine 416 mg Amino Acid profile may vary Essential Amino Acids

Storage

Note: Product is packaged with a desiccant. Store in a cool, dark, dry place. No refrigeration required.

Brand IP Statement(s)

Copyright 2020 Bulletproof 360, Inc. All rights reserved.

Precautions

Processed in a facility that also processes milk, fish, crustacean shellfish, tree nuts, wheat, and soybeans.

As with any supplement, consult your healthcare practitioner before use, particularly if you are pregnant, nursing, taking medications or have a medical condition.

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

See for yourself

Collagen Protein Unflavored by Bulletproof label

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

Collagen Protein Unflavored 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 Collagen Protein Unflavored by Bulletproof

These are the 3 active ingredients this product is made of. Select any to open its full monograph.

Serving size20 Gram(s) Dosage formPowder Servings per container20 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
80 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

Protein

18 Gram(s) per serving

Hydrolyzed Collagen

No known
interactions
20 Gram(s) per serving

Collagen peptides are a well-absorbed form of protein that may modestly improve skin elasticity and joint comfort for some people, though evidence is...

Hydrolyzed Collagen monograph & interactions
Interaction report

Collagen Protein Unflavored by Bulletproof Drug Interactions

Want to check YOUR meds against Collagen Protein Unflavored?

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
207Drugs
101 Moderate 106 Minor

Ingredients driving the most interactions

Vitamin C 207

Individual Drug Interactions

The ingredients in Collagen Protein Unflavored interact with 207 drugs. Click any drug to see the details.

1 of the 3 ingredients in Collagen Protein Unflavored interact with drugs. Each result below shows which ingredient is responsible. Vitamin C

Each ingredient & the kinds of drugs it affects

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

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 Collagen Protein Unflavored, from the product label.

Bulletproof

See all Bulletproof products
Name
Bullet Proof 360 Inc.
City
Seattle
State
WA
ZipCode
98104
Phone Number
1-844-640-3003
Web Address
bulletproof.com
Pharmacist Counseling Corner

Collagen Protein Unflavored by Bulletproof: Common Questions

Does Collagen Protein Unflavored by Bulletproof interact with any medications?
Yes. Based on its ingredients, Collagen Protein Unflavored has a known interaction with 207 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Collagen Protein Unflavored contains 3 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.
Does this product have fillers or anything besides the two active ingredients?
No—the inactive ingredients list is empty, so you're getting just the vitamin C and hydrolyzed collagen.
Will this product affect how well my birth control works?
Vitamin C in this product might increase blood levels of estrogen from oral contraceptives by up to 55% in some cases. That's a Moderate interaction, so talk to your pharmacist or doctor about whether you need dose adjustment or monitoring.
Can I take this if I'm pregnant or breastfeeding?
The vitamin C in normal amounts is considered likely safe in pregnancy and while breastfeeding. However, hydrolyzed collagen hasn't been well studied during pregnancy or nursing, so check with your doctor before using this product if you're pregnant or nursing.
What side effects might I experience?
Vitamin C at high doses (above 2 grams daily) can cause stomach cramps, heartburn, diarrhea, nausea, and headache. Hydrolyzed collagen may rarely cause nausea, indigestion, diarrhea, or gas. At normal supplement doses, both are generally well tolerated.
Does collagen actually help with wrinkles or skin?
Hydrolyzed collagen is possibly effective for aging skin and dry skin based on the evidence we hold, but the research isn't conclusive. Results vary from person to person.
Can I use this if I'm on warfarin (blood thinner)?
No, not without checking with your doctor or pharmacist first. Vitamin C, especially at high doses, can reduce warfarin's blood-thinning effect, which is a Moderate interaction. Your provider may need to adjust your warfarin dose.

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.

Collagen Protein Unflavored label
Go deeper

The Full Monographs Behind Collagen Protein Unflavored’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

Collagen Peptides

Collagen peptides are a well-absorbed form of protein that may modestly improve skin elasticity and joint comfort for some people, though evidence is still developing and results vary. They...

Read the full Collagen Peptides monograph →
Sources

Sources & How We Checked

Collagen Protein Unflavored'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 53 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.
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See these in context on the Vitamin C monograph →

Collagen Peptides 2 references
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  2. Evans M, Lewis ED, Zakaria N, Pelipyagina T, Guthrie N. A randomized, triple-blind, placebo-controlled, parallel study to evaluate the efficacy of a freshwater marine collagen on skin wrinkles and elasticity. J Cosmet Dermatol. 2021;20(3):825-834. PubMed

See these in context on the Collagen Peptides monograph →

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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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