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Dietary supplement

Folic Acid 400 mcg Ingredients & Drug Interactions

by Rugby

Folic Acid 400 mcg label
See full label image
Tablet Or Pill Category: Vitamin
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 Folic Acid 400 mcg 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

Folic Acid 400 mcg is a dietary supplement by Rugby with 1 active ingredient. Its ingredients are commonly taken for preventing neural tube birth defects, treating or preventing folate deficiency, supporting pregnancy health.Based on those ingredients, 40 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Folic Acid. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Folic Acid 400 mcg by Rugby

Ask about any prescription or over-the-counter medication and we check it for interactions with Folic Acid 400 mcg by Rugby — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Folic Acid 400 mcg by Rugby

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 30, 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 1 of its 1 active ingredient.
  • “Folate” is listed as a grouped ingredient — the label gives one combined amount (670 mcg DFE) without saying how much of each component you get.

Rugby's Folic Acid contains one active ingredient: folic acid (vitamin B9) at 400 micrograms per tablet. The inactive ingredients are microcrystalline cellulose, croscarmellose sodium, stearic acid, magnesium stearate, and silica — standard tablet binders and fillers.

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 Folic Acid's overall clinical evidence instead.

Strong

Strong clinical evidence supports Folic Acid 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 ingredient's overall clinical evidence instead.
  • On file: Folate deficiency — rated "Effective" (Natural Medicines).
  • On file: Methotrexate toxicity — rated "Likely Effective" (Natural Medicines).
  • On file: Neural tube birth defects — rated "Likely Effective" (Natural Medicines).
  • On file: Cognitive impairment — rated "Possibly Effective" (Natural Medicines).
  • On file: Depression — rated "Possibly Effective" (Natural Medicines).

Folic acid 400 mcg is effective for preventing and treating folate deficiency. It's also likely effective for reducing methotrexate toxicity (a major concern in cancer treatment) and for preventing neural tube birth defects (spina bifida and anencephaly) when taken during pregnancy.

There is possibly effective evidence for depression, phenytoin-induced gingival hyperplasia (overgrown gums), and cognitive impairment, though the evidence for these uses is less established.

The evidence, ingredient by ingredient Folic Acid

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 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Folic acid at the 400 mcg dose in this product is generally well tolerated in adults. At recommended doses, it's considered safe during pregnancy to help prevent birth defects and safe while breastfeeding at normal recommended levels.

At much higher doses (5–15 mg daily), some people report abdominal cramps, diarrhea, rash, bitter taste, nausea, sleep disturbances, and mood changes. Very rare serious effects at high doses include seizures, liver injury, and cancer with long-term use.

One important caution: folic acid can mask the symptoms of pernicious anemia (a B12 deficiency), which if left untreated can cause permanent nerve damage — don't self-treat suspected anemia without talking to your doctor first.

Side effects, ingredient by ingredient Folic Acid

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 1 matched ingredient can interact with medications — Folic Acid.
  • The most serious interaction on file is rated Moderate.
  • For scale: 40 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before taking this product, check with your doctor or pharmacist if you take seizure medications (phenobarbital, phenytoin, primidone), cancer treatments (methotrexate, capecitabine, 5-fluorouracil), or the antiparasitic pyrimethamine. All of these have Moderate interactions with folic acid where the supplement can reduce drug effectiveness or increase toxicity.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with strong clinical evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

Rugby's Folic Acid 400 mcg works well for preventing or treating folate deficiency and for supporting a healthy pregnancy. If you take seizure medications, cancer drugs, or antiparasitics, this supplement is not safe to add on your own — check with your doctor or pharmacist first.

If you have any concern you might have anemia or B12 deficiency, get that checked before starting folic acid.

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

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Apr 25, 2019.

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

At a glance

General information

Key facts about Folic Acid 400 mcg, straight from the product label.

Brand Rugby
Barcode (UPC) 005363844018
Net contents 100 Tablet(s)
Market status On market
Date entered into DSLD Apr 25, 2019
DSLD ID 200837
Product type Vitamin
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other
Intended target group(s) Vegetarian, Adult (18 - 50 Years), Gluten Free, Sugar 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 Folic Acid 400 mcg by Rugby, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Tablet(s)
Maximum serving Sizes:
1 Tablet(s)
UPC/BARCODE
005363844018
IngredientAmount% DV
Folic Acid400 mcg--
Folate670 mcg DFE168%

Other ingredients: Microcrystalline Cellulose, Croscarmellose Sodium, Stearic Acid, Magnesium Stearate, Silica

Tap any ingredient to jump to its full detail below.

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

Vitamin B Group

FDA Statement of Identity

Dietary Supplement

Precautions

Tamper resistant - Do not use if imprinted safety seal under cap is broken or missing

Consult your doctor before use if you are pregnant, nursing, or taking any medication.

Keep out of reach of children

Suggested/Recommended/Usage/Directions

Directions: Adults - take one tablet daily as a dietary supplement, or as directed by a doctor.

Formulation

Free of starch, sugar, soy, preservatives, yeast, corn, gluten, animal by-products, and artificial color-flavors.

Storage

To preserve quality and freshness, keep bottle tightly closed Store at room temperature and avoid excessive heat.

General

Rev. 01/17 R-95 Re-order No. 370319

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

See for yourself

Folic Acid 400 mcg by Rugby label

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

Folic Acid 400 mcg 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 Folic Acid 400 mcg by Rugby

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Tablet(s) Dosage formTablet Or Pill Amounts shown are per serving.

Folate

670 mcg DFE per serving

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

Interaction report

Folic Acid 400 mcg by Rugby Drug Interactions

Want to check YOUR meds against Folic Acid 400 mcg?

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
40Drugs
40 Moderate

Ingredients driving the most interactions

Folic Acid 40

Individual Drug Interactions

The ingredients in Folic Acid 400 mcg interact with 40 drugs. Click any drug to see the details.

1 of the 1 ingredient in Folic Acid 400 mcg interact with drugs. Each result below shows which ingredient is responsible. Folic Acid

Each ingredient & the kinds of drugs it affects

For each ingredient in Folic Acid 400 mcg 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.

Folic Acid7 drug types · 40 drugs

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.

Likelihood Possible Evidence D
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.

Likelihood Possible Evidence D
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.

Likelihood Probable Evidence B
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.

Likelihood Probable Evidence B
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.

Likelihood Probable Evidence B
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.

Likelihood Probable Evidence B
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.

Likelihood Probable Evidence D
Folic Acid full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Folic Acid 400 mcg, from the product label.

Rugby

See all Rugby products
Name
Rugby Laboratories
Street Address
17177 N Laurel Park Drive, Suite 233
City
Livonia
State
MI
ZipCode
48152
Phone Number
1-800-645-2158
Web Address
www.rugbylaboratories.com
Pharmacist Counseling Corner

Folic Acid 400 mcg by Rugby: Common Questions

Does Folic Acid 400 mcg by Rugby interact with any medications?
Yes. Based on its ingredients, Folic Acid 400 mcg has a known interaction with 40 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Folic Acid 400 mcg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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.
Is 400 mcg a safe dose of folic acid?
Yes, folic acid at 400 mcg is generally well tolerated in adults. At this dose, the adverse effects seen with much higher doses (5–15 mg daily) are not expected.
Is it safe to take folic acid during pregnancy?
Folic acid at recommended prenatal doses is recommended during pregnancy to help prevent birth defects like spina bifida. However, some population research suggests folic acid taken late in pregnancy may be linked to a slightly higher risk of childhood asthma — discuss the best timing with your doctor.
Can I take folic acid while breastfeeding?
Yes, folic acid at normal recommended doses is considered safe while breastfeeding.
What does folic acid do in the body?
Folic acid (vitamin B9) is needed for cell division, DNA synthesis, and proper blood cell formation. It's especially important during pregnancy for fetal development and for preventing birth defects.
What's the difference between folic acid and folate?
Folate is the natural form of vitamin B9 found in foods; folic acid is the synthetic form used in supplements and fortified foods. Your body converts both into the active form it needs.
Can folic acid cause side effects at this dose?
At 400 mcg, side effects are very uncommon. Doses of 5 mg or higher daily can cause abdominal cramps, diarrhea, rash, nausea, and sleep problems in some people.

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.

Folic Acid 400 mcg label
Go deeper

The Full Monographs Behind Folic Acid 400 mcg’s Ingredients

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

Herb & supplement monograph

Folic Acid

Interacts with 40 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 taken before and during early pregnancy. I...

Read the full Folic Acid monograph →
Sources

Sources & How We Checked

Folic Acid 400 mcg'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 56 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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  10. Morgan SL, Baggott JE, Lee JY, Alarcón GS. Folic acid supplementation prevents deficient blood folate levels and hyperhomocysteinemia during longterm, low dose methotrexate therapy for rheumatoid arthritis: implications for cardiovascular disease preventi
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  50. Wehby GL, Félix TM, Goco N, Richieri-Costa A, Chakraborty H, Souza J, Pereira R, Padovani C, Moretti-Ferreira D, Murray JC. High dosage folic acid supplementation, oral cleft recurrence and fetal growth. Int J Environ Res Public Health. 2013 4;10(2):590-6 PubMed
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  53. Houghton LA, Sherwood KL, Pawlosky R, Ito S, O'Connor DL. [6S]-5-Methyltetrahydrofolate is at least as effective as folic acid in preventing a decline in blood folate concentrations during lactation. Am J Clin Nutr. 2006 Apr;83(4):842-50. PubMed
  54. Houghton LA, Yang J, O'Connor DL. Unmetabolized folic acid and total folate concentrations in breast milk are unaffected by low-dose folate supplements. Am J Clin Nutr. 2009 Jan;89(1):216-20. PubMed
  55. Chan SL, Chan AWH, Mo F, et al. Association Between Serum Folate Level and Toxicity of Capecitabine During Treatment for Colorectal Cancer. Oncologist. 2018 Dec;23(12):1436-1445. PubMed
  56. Sarris J, Ravindran A, Yatham LN, et al. Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety T

See these in context on the Folic Acid 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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