Folic Acid Plus Ingredients & Drug Interactions
What is this page for?
First and foremost: checking Folic Acid Plus 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
Folic Acid Plus is a dietary supplement by Nature's Sunshine with 2 active ingredients. Its ingredients are commonly taken for preventing neural tube birth defects, treating or preventing folate deficiency, supporting pregnancy health.Based on those ingredients, 246 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Vitamin C, Folic Acid. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against Folic Acid Plus by Nature's Sunshine
Ask about any prescription or over-the-counter medication and we check it for interactions with Folic Acid Plus by Nature's Sunshine — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
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HelloPharmacist Scorecard of Folic Acid Plus by Nature's Sunshine
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.
What’s inside
Full disclosure
Folic Acid Plus contains two active ingredients: folic acid and vitamin C. Folic acid is a B vitamin that supports cell division and DNA synthesis, and it's used to prevent and treat folate deficiency—a cause of anemia—as well as to help prevent neural tube birth defects during pregnancy.
Vitamin C is an antioxidant and essential nutrient that supports immune function and collagen formation. The product also includes inactive ingredients: cellulose, di-calcium phosphate, bee pollen, and magnesium stearate, which are fillers and binders that hold the tablet together.
Does it work?
Strong evidence
Folic acid in this product is effective for treating folate deficiency and likely effective for reducing methotrexate toxicity and preventing neural tube birth defects in pregnancy. There's also possibly effective evidence for its use in depression, phenytoin-induced gum overgrowth, and cognitive impairment, though the evidence is less robust.
Vitamin C is effective for vitamin C deficiency. It's possibly effective for several other uses in our data: anemia of chronic disease, atrial fibrillation, cataracts, and preventing exercise-related respiratory infections.
Keep in mind that the evidence for these less-established uses is still developing.
How safe is it?
Well-documented data
Folic acid is generally well tolerated at recommended doses for most adults and is recommended at standard prenatal doses to help prevent birth defects. It's also considered safe at normal recommended doses while breastfeeding.
At higher doses (5 mg daily or more), some people report abdominal cramps, diarrhea, and rash; at 15 mg daily, confusion, irritability, nausea, and sleep disturbances have occurred. Rare serious effects at high doses include seizures, liver injury, and cardiovascular complications.
Very high folic acid doses can also worsen nerve damage in people who are deficient in vitamin B12, and taking it without diagnosis can mask symptoms of pernicious anemia. Vitamin C is generally well tolerated at normal dietary and supplement doses.
At very high doses (above 2 grams daily), it commonly causes abdominal cramps, heartburn, nausea, diarrhea, and headache, and kidney stones have been reported in susceptible people. There is a caution about high-dose vitamin C in late pregnancy—population research has associated it with slightly increased risk of childhood asthma, wheeze, and respiratory infections up to 18 months of age, though pre-pregnancy and early pregnancy use have not shown this link.
At normal prenatal doses, vitamin C is considered safe; avoid high-dose supplements in pregnancy unless your doctor advises otherwise. For breastfeeding, recommended dietary amounts are safe, but avoid high-dose supplements unless directed by your healthcare provider.
Meds to double-check
Moderate interaction found
Before taking Folic Acid Plus, double-check with your doctor or pharmacist if you take seizure medications (phenobarbital, phenytoin, primidone), cancer treatments (methotrexate, capecitabine, 5-fluorouracil, alkylating agents, antitumor antibiotics), blood thinners (warfarin), antiparasitic drugs (pyrimethamine), estrogen-based medications (oral contraceptives, hormone replacement therapy), thyroid medication (levothyroxine), HIV protease inhibitors (indinavir), antipsychotics (fluphenazine), or aluminum-containing compounds. All of these have documented moderate interactions with ingredients in this product.
The bottom line
Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.
This product can work well if you need to prevent or treat folate deficiency or support folate intake during pregnancy, and the vitamin C adds antioxidant support. However, because of the interactions with seizure medications, cancer treatments, blood thinners, oral contraceptives, thyroid medication, and other drugs, you'll need to check your exact medications with your doctor or pharmacist before you start.
If you're taking any prescription medication, do not begin this supplement without clearing it first.
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 Sep 24, 2019.
This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed
General information
Key facts about Folic Acid Plus, straight from the product label.
| Brand | Nature's Sunshine |
|---|---|
| Barcode (UPC) | 099904015852 |
| Net contents | 90 Tablet(s) |
| Market status | On market |
| Date entered into DSLD | Sep 24, 2019 |
| DSLD ID | 207144 |
| Product type | Vitamin |
| Supplement form | Tablet Or Pill |
| Dietary claims / uses | Nutrient, All Other, Approved Health, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years), Kosher, Pregnant Women |
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 Folic Acid Plus by Nature's Sunshine, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| Folic Acid | 800 mcg | 200% |
| Vitamin C | 240 mcg | 400% |
Other ingredients: Cellulose, Di-Calcium Phosphate, Bee Pollen, Magnesium Stearate
Tap any ingredient to jump to its full detail below.
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.
General Statements
010015850314
Nature's Sunshine uses natural source materials that are subject to color variation.
Product of U.S.A. Since 1972 Quality, service, integrity
Guaranteed pure Glandular system support
Formula
Folic acid is essential for human health, especially for the developing fetus. Healthful diets with adequate folic acid may reduce a woman's risk of having a child with a brain or neural tube birth defect. It is important for pregnant women, and women planning pregnancy, to receive 400 mcg of folic acid per day.
It is important for pregnant women, and women planning pregnancy, to receive 400 mcg of folic acid per day.
Ko Pareve
Suggested/Recommended/Usage/Directions
Recommendation: Take one or two tablets daily with a meal.
FDA Disclaimer Statement
This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Precautions
This bottle was sealed for your protection. Do not use if inner seal is missing or damaged.
Brand IP Statement(s)
2014 Nature's Sunshine Products, Inc.
FDA Statement of Identity
Dietary Supplement
Seals/Symbols
Ko Pareve
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
Folic Acid Plus by Nature's Sunshine label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
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)The Ingredients in Folic Acid Plus by Nature's Sunshine
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 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.
Folic Acid
Interacts with40 drugs
Folic acid is the man-made form of vitamin B9 and is one of the most well-studied supplements, especially for preventing serious birth defects when ta...
Folic Acid monograph & interactionsVitamin C
Interacts with207 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 im...
Vitamin C monograph & interactionsOther (inactive) ingredients: Cellulose, Di-Calcium Phosphate, Bee Pollen, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.
Folic Acid Plus by Nature's Sunshine Drug Interactions
HelloPharmacist Interaction Report
Folic Acid Plus by Nature's Sunshine interacts with medications through both its folic acid and vitamin C content.
The most serious interaction we have on record is folic acid's effect on seizure medications: it can antagonize phenobarbital and primidone, reversing their seizure control and increasing seizure risk, and may reduce phenytoin levels, also raising seizure frequency.
Read the full breakdown — every affected drug type, severity by severity
Folic acid poses moderate interactions with cancer drugs (methotrexate, capecitabine, and 5-fluorouracil) by potentially reducing their effectiveness or increasing their toxicity. It also antagonizes pyrimethamine, an antiparasitic medication used for certain infections like toxoplasmosis.
Vitamin C carries moderate interactions with blood thinners (warfarin—high-dose vitamin C may reduce its effectiveness), estrogen-based drugs like oral contraceptives and hormone replacement therapy (vitamin C may increase estrogen levels), chemotherapy agents including alkylating agents and antitumor antibiotics (antioxidant effects may lower drug activity), thyroid medication (levothyroxine—vitamin C increases its absorption), and HIV protease inhibitors (indinavir levels may drop modestly). Vitamin C can also increase aluminum absorption from aluminum-containing compounds and theoretically decrease antipsychotic levels (fluphenazine).
Altogether, these interactions span 246 individual medications. Run your exact prescriptions through the medication checker below before you start.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against Folic Acid Plus?
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 checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in Folic Acid Plus interact with 246 drugs. Click any drug to see the details.
2 of the 2 ingredients in Folic Acid Plus interact with drugs. Each result below shows which ingredient is responsible. Vitamin C Folic Acid
Alginic Acid, Aluminum HydroxideRafton
How Alginic Acid, Aluminum Hydroxide interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Alginic Acid, Aluminum Hydroxide interactionAltretamineHexalen
How Altretamine interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAlkylating Agents Moderate
Interaction Summary
Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
Read the full Vitamin C + Altretamine interactionAluminum Acetate, Benzethonium ChlorideBuro-Sol Otic Solution
How Aluminum Acetate, Benzethonium Chloride interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum Acetate, Benzethonium Chloride interactionAluminum ChlorideAluminum Chloride, Anhydrol Forte, Driclor, Drysol
How Aluminum Chloride interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum Chloride interactionAluminum HydroxideAlu-Cap, Amphojel, Gaviscon
How Aluminum Hydroxide interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum Hydroxide interactionAluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #2
How Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium Hydroxide interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAspirin, Aluminum Moderate
Interaction Summary
Acidification of the urine by vitamin C might increase aspirin levels.
Read the full Vitamin C + Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium Hydroxide interactionAluminum Hydroxide, Aspirin, Magnesium HydroxideAscriptin
How Aluminum Hydroxide, Aspirin, Magnesium Hydroxide interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAspirin, Aluminum Moderate
Interaction Summary
Acidification of the urine by vitamin C might increase aspirin levels.
Read the full Vitamin C + Aluminum Hydroxide, Aspirin, Magnesium Hydroxide interactionAluminum Hydroxide, Magnesium Hydroxide (otc Drug)Maalox, Mucogel
How Aluminum Hydroxide, Magnesium Hydroxide (otc Drug) interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum Hydroxide, Magnesium Hydroxide (otc Drug) interactionAluminum Hydroxide, Magnesium Hydroxide, Simethicone (otc Drug)Mylanta
How Aluminum Hydroxide, Magnesium Hydroxide, Simethicone (otc Drug) interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum Hydroxide, Magnesium Hydroxide, Simethicone (otc Drug) interactionAluminum, CalciumDomeboro
How Aluminum, Calcium interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum, Calcium interactionAluminum, Magnesium (otc Drug)Almagel
How Aluminum, Magnesium (otc Drug) interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum, Magnesium (otc Drug) interactionAluminum, Magnesium Hydroxide (otc Drug)Wingel
How Aluminum, Magnesium Hydroxide (otc Drug) interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAluminum Moderate
Interaction Summary
Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
Read the full Vitamin C + Aluminum, Magnesium Hydroxide (otc Drug) interactionAprobarbital, Butabarbital, PhenobarbitalTriple Barbital
How Aprobarbital, Butabarbital, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Aprobarbital, Butabarbital, Phenobarbital interactionAspirin, Aluminum Hydroxide, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #3
How Aspirin, Aluminum Hydroxide, Codeine Phosphate, Magnesium Hydroxide interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAspirin, Aluminum Moderate
Interaction Summary
Acidification of the urine by vitamin C might increase aspirin levels.
Read the full Vitamin C + Aspirin, Aluminum Hydroxide, Codeine Phosphate, Magnesium Hydroxide interactionAspirin, Codeine Phosphate, PhenobarbitalPhenaphen
How Aspirin, Codeine Phosphate, Phenobarbital interacts with Folic Acid Plus — through 2 ingredients. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Aspirin, Codeine Phosphate, Phenobarbital interactionVitamin CAspirin Minor
Interaction Summary
Acidification of the urine by vitamin C might increase aspirin levels.
Read the full Vitamin C + Aspirin, Codeine Phosphate, Phenobarbital interactionAtropine, Hyoscyamine, PhenobarbitalHypnaldyne
How Atropine, Hyoscyamine, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Atropine, Hyoscyamine, Phenobarbital interactionAtropine, Hyoscyamine, Phenobarbital, ScopolamineBarbidonna No. 2, Belladonna Phenobarbital
How Atropine, Hyoscyamine, Phenobarbital, Scopolamine interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Atropine, Hyoscyamine, Phenobarbital, Scopolamine interactionAtropine, Hyoscyamine, Scopolamine, PhenobarbitalBarbeloid, Donnatal #2, Donphen
How Atropine, Hyoscyamine, Scopolamine, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Atropine, Hyoscyamine, Scopolamine, Phenobarbital interactionAtropine, PhenobarbitalAnthrocol
How Atropine, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Atropine, Phenobarbital interactionBazedoxifene Acetate, Conjugated EstrogensDuavee
How Bazedoxifene Acetate, Conjugated Estrogens interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CEstrogens Moderate
Interaction Summary
Vitamin C might increase blood levels of estrogens.
Read the full Vitamin C + Bazedoxifene Acetate, Conjugated Estrogens interactionBelladona Extract, PhenobarbitalChardonna-2
How Belladona Extract, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladona Extract, Phenobarbital interactionBelladonna Alkaloids, Ergotamine Tartrate, PhenobarbitalBel Tabs, Bellamine-S, Bellaphen-S, Duragal S, Phenarbal S, Spastrin
How Belladonna Alkaloids, Ergotamine Tartrate, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladonna Alkaloids, Ergotamine Tartrate, Phenobarbital interactionBelladonna Alkaloids, PhenobarbitalBarbidonna, Donnatal
How Belladonna Alkaloids, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladonna Alkaloids, Phenobarbital interactionBelladonna Extract, PhenobarbitalBelap
How Belladonna Extract, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladonna Extract, Phenobarbital interactionBelladonna, Ergotamine Tartrate, Phenobarbital
How Belladonna, Ergotamine Tartrate, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladonna, Ergotamine Tartrate, Phenobarbital interactionBelladonna, Ergotamine, PhenobarbitalBellergal-S
How Belladonna, Ergotamine, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladonna, Ergotamine, Phenobarbital interactionBelladonna, PhenobarbitalBellophen, Susano
How Belladonna, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Belladonna, Phenobarbital interactionBellafoline, PhenobarbitalBelladenal, Belladenal-S
How Bellafoline, Phenobarbital interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Folic AcidPhenobarbital (luminal) Moderate
Interaction Summary
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Read the full Folic Acid + Bellafoline, Phenobarbital interactionBendamustineBelrapzo, Treanda, Vivimusta
How Bendamustine interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAlkylating Agents Moderate
Interaction Summary
Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
Read the full Vitamin C + Bendamustine interactionBendamustine HydrochlorideBendeka
How Bendamustine Hydrochloride interacts with Folic Acid Plus — through 1 ingredient. Tap an ingredient for the detail:
Vitamin CAlkylating Agents Moderate
Interaction Summary
Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
Read the full Vitamin C + Bendamustine Hydrochloride interactionEach ingredient & the kinds of drugs it affects
For each ingredient in Folic Acid Plus 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.
Vitamin C
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Folic Acid
5-Fluorouracil
Theoretically, high doses of folic acid might increase the toxicity of 5-fluorouracil.
Increases in gastrointestinal side effects of 5-fluorouracil, such as stomatitis and diarrhea, have been described in two clinical studies when leucovorin, a form of folic acid, was administered with 5-fluorouracil.
Capecitabine (Xeloda)
Use of high-dose folic acid might contribute to capecitabine toxicity.
Clinical research suggests that higher serum folate levels are associated with an increased risk for moderate or severe toxicity during capecitabine-based treatment for colorectal cancer. Additionally, in one case report, taking folic acid 15 mg daily might have contributed to increased toxicity, including severe diarrhea, vomiting, edema, hand-foot syndrome, and eventually death, in a patient prescribed capecitabine.
Methotrexate (Trexall, Others)
Folic acid might reduce the efficacy of methotrexate as a cancer treatment when given concurrently.
Methotrexate exerts its cytotoxic effects by preventing conversion of folic acid to the active form needed by cells. There is some evidence that folic acid supplements reduce the efficacy of methotrexate in the treatment of acute lymphoblastic leukemia, and theoretically they could reduce its efficacy in the treatment of other cancers. Advise cancer patients to consult their oncologist before using folic acid supplements. In patients treated with long-term, low-dose methotrexate for rheumatoid arthritis (RA) or psoriasis, folic acid supplements can reduce the incidence of side effects, without reducing efficacy.
Phenobarbital (Luminal)
Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Folic acid can have direct convulsant activity in some people, reversing the effects of phenobarbital and worsening seizure control. Monitor closely for increased seizure activity.
Phenytoin (Dilantin)
Folic acid might reduce serum levels of phenytoin in some patients.
Folic acid may be a cofactor in phenytoin metabolism. Folic acid, in doses of 1 mg daily or more, can reduce serum levels of phenytoin in some patients. Increases in seizure frequency have been reported. If folic acid supplements are added to established phenytoin therapy, monitor serum phenytoin levels closely. If phenytoin and folic acid are started at the same time and continued together, adverse changes in phenytoin pharmacokinetics are avoided. Note that phenytoin also reduces serum folate levels.
Primidone (Mysoline)
Folic acid might have antagonistic effects on primidone and increase the risk for seizures.
Folic acid can have direct convulsant activity in some people, reversing the effects of primidone and worsening seizure control. Monitor closely for increased seizure activity. Note that primidone also reduces serum folate levels.
Pyrimethamine (Daraprim)
Folic acid might antagonize the effects of pyrimethamine.
Folic acid can antagonize the antiparasitic effects of pyrimethamine against toxoplasmosis and Pneumocystis carinii pneumonia. Folic acid doesn't antagonize the effects of pyrimethamine in the treatment of malaria, because malarial parasites cannot use exogenous folic acid. Use folinic acid as an alternative to folic acid when indicated.
Brand information
Manufacturer and brand details for Folic Acid Plus, from the product label.
Nature's Sunshine
See all Nature's Sunshine products- Name
- Nature's Sunshine Products, Inc.
- City
- Spanish Fork
- State
- UT
- ZipCode
- 84660
- Phone Number
- 1-800-223-8225
- Web Address
- www.naturessunshine.com
Folic Acid Plus by Nature's Sunshine: Common Questions
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Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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The Full Monographs Behind Folic Acid Plus’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Folic Acid
Interacts with 40 drugsFolic acid is the man-made form of vitamin B9 and is one of the most well-studied supplements, especially for preventing serious birth defects when taken before and during early pregnancy. I...
Read the full Folic Acid monograph → Herb & supplement monographVitamin C
Interacts with 207 drugsVitamin 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 →Sources & How We Checked
Folic Acid Plus'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.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
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 107 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.
Folic Acid 56 references
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Vitamin C 51 references
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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