Interactions on record — worth a quick check against your medications. Based on 2 of 5 ingredients. Check your meds →
Dietary supplement

Mega MSM Ingredients & Drug Interactions

by U.S. Doctors' Clinical

Mega MSM label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 9, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Mega MSM 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

Mega MSM is a dietary supplement by U.S. Doctors' Clinical with 5 active ingredients. Its ingredients are commonly taken for common cold and immune support, antioxidant support, skin health and collagen formation.Based on those ingredients, 1,086 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Neem, Vitamin C. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Mega MSM by U.S. Doctors' Clinical

Ask about any prescription or over-the-counter medication and we check it for interactions with Mega MSM by U.S. Doctors' Clinical — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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HelloPharmacist Scorecard of Mega MSM by U.S. Doctors' Clinical

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 Aug 20, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 2 of its 5 active ingredients.
  • “Collaplex” is listed as a grouped ingredient — the label gives one combined amount (220 mg) without saying how much of each component you get.

Mega MSM contains 5 active ingredients. Vitamin C supports immune function and acts as an antioxidant.

MSM is a sulfur compound sometimes used for joint and connective tissue support. Collagen is a structural protein.

Corydalis is a plant extract. Neem is a tree leaf used traditionally in herbal medicine.

The capsules also contain gelatin, silicon dioxide, magnesium stearate, and titanium dioxide as inactive ingredients that help form and preserve the capsule.

Does it work?

Strong 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

This product doesn't appear to be marketed for a specific use, so we graded its ingredients' overall clinical evidence instead.

Strong

Strong clinical evidence supports its ingredients for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredients' overall clinical evidence instead.
  • On file: Vitamin C deficiency — rated "Effective" (Vitamin C) (Natural Medicines).
  • On file: Hypertension — rated "Possibly Effective" (Vitamin C) (Natural Medicines).
  • On file: Hypercholesterolemia — rated "Possibly Effective" (Vitamin C) (Natural Medicines).
  • On file: Atrial fibrillation — rated "Possibly Effective" (Vitamin C) (Natural Medicines).
  • On file: Laser skin resurfacing — rated "Possibly Effective" (Vitamin C) (Natural Medicines).

The data we hold shows vitamin C is effective for vitamin C deficiency, and possibly effective for anemia related to chronic disease, atrial fibrillation, cataracts, and exercise-induced respiratory infections. For neem, the evidence supports it as possibly effective for gingivitis, dental plaque, and head lice.

We don't have established evidence in our data for MSM, collagen, or corydalis, and we also don't have effectiveness ratings for how this specific combination works for any particular condition.

The evidence, ingredient by ingredient Vitamin C Neem

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 doses, but high amounts—above 2 grams daily—can cause abdominal cramps, heartburn, diarrhea, nausea, and headache. In people prone to kidney stones, very high doses carry a small risk.

Neem leaf preparations appear safe short-term in adults when taken by mouth, though comprehensive safety testing hasn't been done. The safety data advises against neem during pregnancy and lactation.

Because vitamin C safety notes caution against high-dose supplements in pregnancy unless your doctor advises otherwise, and neem is considered likely unsafe in pregnancy, talk with your doctor or pharmacist before taking this product if you're pregnant or breastfeeding.

Side effects, ingredient by ingredient Vitamin C Neem

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 — Neem, Vitamin C.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; cancer treatments; diabetes medications.
  • For scale: 1,087 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 before combining with birth control or hormone replacement therapy (estrogens), blood thinners like warfarin, thyroid medication (levothyroxine), chemotherapy drugs, diabetes medications, antipsychotics, HIV antivirals, and any drug your liver breaks down or that requires a protein pump (P-glycoprotein) to work. Also mention immunosuppressants and any allergy or sensitivity history.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with strong clinical evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

If you take birth control, hormone therapy, thyroid medication, blood thinners, chemotherapy, diabetes drugs, or medications processed through your liver, check with your doctor or pharmacist before starting this product. Vitamin C at high doses and neem both carry specific concerns with certain medications.

If you're pregnant or breastfeeding, discuss it with your healthcare provider first.

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

Assessment coverage: 2 of 5 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Apr 25, 2018.

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 Mega MSM, straight from the product label.

Brand U.S. Doctors' Clinical
Barcode (UPC) 851743006374
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Apr 25, 2018
DSLD ID 176504
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) 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 Mega MSM by U.S. Doctors' Clinical, 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:
2 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
45
UPC/BARCODE
851743006374
IngredientAmount% DV
Vitamin C20 mg33%
MSM1200 mg--
Collagen0 NP--
Corydalis0 NP--
Neem0 NP--
Collaplex220 mg--

Other ingredients: Gelatin, Silicon Dioxide, Magnesium Stearate, Titanium Dioxide

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.
Precautions

Warning: Women who are pregnant or lactating should consult a health care professional before using any nutritional product.

If any adverse reactions occur, discontinue use and consult a health care professional.

Not for use by children under the age 18. Keep bottle tightly closed and out of reach of children.

Do not use if seal under cap has been broken.

Do not take this supplement within one hour of taking medications.

Do not exceed the recommended dosage.

Storage

Keep bottle tightly closed and out of reach of children. Store in a cool, dry place.

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.

General

Product No. DC0031 - No. 2

Seals/Symbols

cGMP

Made in U.S.A.

Gluten free

General Statements

Clinically proven Nourishes cartilage and support joint health Over 3 million sold

~ Supports healthy joint formation and joint comfort ~ Supports hydration and flexibility in healthy joints

FDA Statement of Identity

Dietary Supplement

Formulation

Gluten free

Suggested/Recommended/Usage/Directions

Directions: For adults only. Take two (2) capsules twice daily during or after morning and afternoon meals.

Brand IP Statement(s)

PureWay-C is a registered trademark of Innovation Laboratories, Inc.

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

See for yourself

Mega MSM by U.S. Doctors' Clinical label

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

Mega MSM 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 Mega MSM by U.S. Doctors' Clinical

These are the 5 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 Capsule(s) Dosage formCapsule Servings per container45 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
20 mg per serving

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

MSM

1200 mg per serving

Collaplex

220 mg per serving
  • › Collagen
  • › Corydalis
  • › Neem

Other (inactive) ingredients: Gelatin, Silicon Dioxide, Magnesium Stearate, Titanium Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Mega MSM by U.S. Doctors' Clinical Drug Interactions

Want to check YOUR meds against Mega MSM?

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
1,086Drugs
1,064 Moderate 22 Minor

Ingredients driving the most interactions

Neem 1,013
Vitamin C 207

Individual Drug Interactions

The ingredients in Mega MSM interact with 1,086 drugs. Click any drug to see the details.

2 of the 5 ingredients in Mega MSM interact with drugs. Each result below shows which ingredient is responsible. Neem Vitamin C

Each ingredient & the kinds of drugs it affects

For each ingredient in Mega MSM 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.

Neem7 drug types · 1,013 drugs

Antidiabetes Drugs

Neem might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Some clinical research shows that neem can lower blood glucose levels in adults with type 2 diabetes, including those already taking metformin.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that neem leaf extract inhibits CYP1A2 enzymes. So far, this reaction has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C8 (Cyp2C8) Substrates

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP2C8 substrates.
In vitro research shows that neem leaf methanol extract inhibits CYP2C8 enzymes. So far, this reaction has not been reported in humans.

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

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP2C9 substrates.
In vitro research shows that neem leaf methanol extract inhibits CYP2C9 enzymes. So far, this reaction has not been reported in humans.

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

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that neem leaf methanol extract inhibits CYP3A4 enzymes. So far, this reaction has not been reported in humans.

Likelihood Possible Evidence D
Immunosuppressants

Theoretically, neem might decrease the effectiveness of immunosuppressants.
Animal research suggests that neem might have immunostimulant effects.

Likelihood Possible Evidence D
P-Glycoprotein Substrates

Theoretically, neem leaf extract might increase the levels and clinical effects of P-glycoprotein substrates.
In vitro research shows that neem leaf methanol extract inhibits renal P-glycoprotein transport activity. So far, this reaction has not been reported in humans.

Likelihood Possible Evidence D
Neem 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 Mega MSM, from the product label.

U.S. Doctors' Clinical

See all U.S. Doctors' Clinical products
Name
U.S. Doctors' Clinical
Street Address
15568 Brookhurst St. Ste. 374
City
Westminster
State
CA
ZipCode
92683
Phone Number
1-800-914-0594
Web Address
www.usdoctorsclinical.com
Pharmacist Counseling Corner

Mega MSM by U.S. Doctors' Clinical: Common Questions

Does Mega MSM by U.S. Doctors' Clinical interact with any medications?
Yes. Based on its ingredients, Mega MSM has a known interaction with 1,086 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Mega MSM contains 5 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 pill?
Vitamin C in this product can increase estrogen levels, and research shows increases up to 55% are possible when vitamin C is taken with oral contraceptives. This could affect how well your birth control works. Talk to your doctor or pharmacist about whether this product is right for you if you're on hormonal birth control.
Can I take this if I'm on warfarin (Coumadin)?
No, not without checking first. High-dose vitamin C can reduce how well warfarin works by lowering its levels in your blood. This is a serious interaction, so your doctor or pharmacist needs to know before you add this product.
Is neem safe to take every day?
The data we hold shows neem leaf extracts appear well tolerated short-term in adults, but high-quality safety studies haven't been completed, so long-term daily use isn't well established. It should be avoided during pregnancy and breastfeeding.
What is MSM, and does it do anything?
MSM is a sulfur compound that's sometimes added to joint-support products, but the facts provided don't include effectiveness data for it, so I can't tell you whether this product supports that claim.
Could this cause kidney stones?
Vitamin C, especially in high doses, has been linked to kidney stones in people who are prone to them. If you have a history of kidney stones, mention this product to your doctor or pharmacist before taking it.
Is this safe during pregnancy?
The data advises against high-dose vitamin C supplements in pregnancy unless directed by your doctor, and neem is considered likely unsafe during pregnancy. Talk with your doctor or pharmacist for personalized advice before taking this product if you're pregnant.

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.

Mega MSM label
Go deeper

The Full Monographs Behind Mega MSM’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

Neem

Interacts with 1,013 drugs

Neem is a tree from India used for centuries in traditional medicine, especially for skin, dental, and antimicrobial purposes. Some small studies are promising for oral health and skin, but...

Read the full Neem monograph →
Sources

Sources & How We Checked

Mega MSM'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 79 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
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  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
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Neem 28 references
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See these in context on the Neem 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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