Drug & supplement interaction

Vitamin A + Sulfadiazine

Sulfadiazine brand name: Sulfadiazine.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Vitamin A has a moderate interaction with Sulfadiazine. Theoretically, taking high doses of vitamin A in combination with other potentially hepatotoxic drugs might increase the risk of liver disease.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

Vitamin A and Sulfadiazine

Here is the interaction we found between these two, with the evidence behind it.

Moderate

HEPATOTOXIC DRUGS

Why this applies to Sulfadiazine

Sulfadiazine falls under HEPATOTOXIC DRUGS — the group Vitamin A interacts with.

Theoretically, taking high doses of vitamin A in combination with other potentially hepatotoxic drugs might increase the risk of liver disease.
The tolerable upper intake level (UL) is the highest level of intake that is likely to pose no risk of adverse effects. Doses of vitamin A above the UL can cause hepatotoxicity, ranging from elevated liver enzymes to liver failure.
Severity Moderate Likelihood Possible Evidence C

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version: this isn't about one drug speeding up or slowing down the other. Both vitamin A in high doses and sulfadiazine can, on their own, put some stress on the liver. The worry is mostly theoretical, and it's about stacking two liver stressors at the same time, not a direct chemical clash.

For most people taking sulfadiazine for a urinary tract infection, the everyday amount of vitamin A from food or a standard multivitamin is very unlikely to cause trouble. The real caution is with large, concentrated vitamin A supplements taken above the recommended upper limit. If you notice yellowing skin or eyes, dark urine, belly pain, or unusual tiredness, contact your pharmacist or doctor promptly rather than changing anything yourself.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  2. Fritz, H., Kennedy, D., Fergusson, D., Fernandes, R., Doucette, S., Cooley, K., Seely, A., Sagar, S., Wong, R., and Seely, D. Vitamin A and retinoid derivatives for lung cancer: a systematic review and meta analysis. PLoS.One. 2011;6(6):e21107. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Vitamin A Also Interacts With Other Medications

Vitamin A has 9 major, 377 moderate known drug interactions in our database — the Sulfadiazine one above is one of them. If you take anything else, check it against the full list below.

Major 9 Moderate 377 No known interaction 2,444 (incl. Sulfadiazine)
Taking anything else?

Check Another of Your Medications Against Vitamin A

Covers the 2,830 medications we’ve checked against Vitamin A. Pick one to open its full report.

From our Q&A

Questions About Vitamin A or Sulfadiazine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Vitamin A or Sulfadiazine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Sulfadiazine

This page covers Vitamin A only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Sulfadiazine page lists 107 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Para-aminobenzoic Acid (paba) (major), Siberian Cocklebur (major) and Wine (major).

By severity: 5 major · 91 moderate · 11 minor.

From our pharmacist’s overview on the Sulfadiazine page

“Sulfadiazine treats serious infections like toxoplasmosis, often over long courses, and its list of 107 interacting supplements calls for real care. The most direct problem is PABA, sold as a B-vitamin relative, because it can blunt sulfadiazine's antibacterial effect outright.”

Reviewed by 2 · Jul 18, 2026

Open the Sulfadiazine interaction page

One more smart check

Taking Vitamin A as Part of a Dietary Supplement Product? Check It for Interactions

We hold 19,215 real supplement products containing Vitamin A, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Vitamin A. Your product may carry other ingredients that interact with Sulfadiazine too, on top of Vitamin A — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Vitamin A and Sulfadiazine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Vitamin A
Top 1%

#11 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Sulfadiazine
Steady interest

#1,543 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Vitamin A

What is Vitamin A?

  • Eye and vision health
  • Skin health and acne
  • Immune support
  • Correcting vitamin A deficiency
  • Childhood growth and development

Vitamin A is an essential nutrient important for vision, skin, immune function, and growth. Most people get enough from a balanced diet, and supplements are mainly useful for correcting a true deficiency. Because vitamin A is fat-soluble and can build up to harmful levels, more is not better, and high doses are especially risky in pregnancy.

Read the full Vitamin A monograph & all interactions
Medication

About Sulfadiazine

What Is Sulfadiazine Used For?

Brand name: Sulfadiazine

Sulfadiazine tablets are used to treat several types of bacterial and parasitic infections. These include urinary tract infections (such as kidney and bladder infections caused by susceptible bacteria), toxoplasmosis encephalitis (a brain infection caused by a parasite), chancroid, trachoma, inclusion conjunctivitis, nocardiosis, meningococcal meningitis, acute otitis media (middle ear infection) due to H. influenzae, and malaria caused by chloroquine-resistant strains — though the last two are used alongside other medicines.

Sulfadiazine tablets are also used to help prevent meningococcal meningitis in close contacts when the bacteria are known to be susceptible, and to prevent recurrences of rheumatic fever as an alternative to penicillin. For urinary tract infections, it should only be used after more soluble sulfonamide options have not worked.

See full Sulfadiazine drug information
Keep checking

Other Drugs & Vitamin A

Browse every other medication we’ve checked against Vitamin A — both the ones with a known interaction and the ones without. Select any drug for the full detail.

9Major
377Moderate
0Minor
2,443No known interaction
9 Major 377 Moderate 2,443 No interaction
Major

9 interactions

Moderate

377 interactions

Showing 60 of 377 moderate interactions — see all 377 on the Vitamin A page.

No interaction 2,443 drugs checked — show the list

We also checked Vitamin A against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,443 medications checked with no known interaction — see the full Vitamin A list.

See the full Vitamin A interactions page
See every supplement checked against Sulfadiazine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

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

Keep exploring
Vitamin A monograph › Uses, safety, and every drug interaction in one place Sulfadiazine supplement interactions › Every supplement checked against Sulfadiazine, ranked by severity Sulfadiazine drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Vitamin A and Sulfadiazine Together: Common Questions

Can you take Vitamin A with Sulfadiazine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Vitamin A and Sulfadiazine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Sulfadiazine and Vitamin A?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.