Drug & supplement interaction

Riboflavin + Mechlorethamine Hydrochloride

Mechlorethamine Hydrochloride brand name: Valchlor.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Riboflavin and Mechlorethamine Hydrochloride in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Riboflavin and Mechlorethamine Hydrochloride

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Mechlorethamine Hydrochloride and Riboflavin in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Riboflavin safety at a glance

Riboflavin overall Generally safe Riboflavin is considered very safe; excess is removed in the urine.
Pregnancy Likely Safe When used orally and appropriately in dietary amounts. A tolerable upper intake level (UL) has not been established. Read the full pregnancy detail
Breastfeeding Likely Safe When used orally and appropriately in dietary amounts. A tolerable upper intake level (UL) has not been established. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Mechlorethamine Hydrochloride and Riboflavin? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Mechlorethamine Hydrochloride

Interactions in our licensed database are recorded against drug classes, not just single drug names. Mechlorethamine Hydrochloride is filed under 2 classifications — alkylating agents, topical drugs. Riboflavin has documented interactions with 1 drug class — the most serious being tetracycline antibiotics (moderate) — and none of Mechlorethamine Hydrochloride’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Riboflavin Does Interact With Other Medications

Riboflavin has 20 moderate known drug interactions in our database — Mechlorethamine Hydrochloride isn’t one of them. If you take anything else, check it against the full list below.

Moderate 20 No known interaction 2,810 (incl. Mechlorethamine Hydrochloride)
Taking anything else?

Check Another of Your Medications Against Riboflavin

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

What to actually watch for

What Riboflavin Itself Has Been Linked To

This is not an interaction — nothing below involves Mechlorethamine Hydrochloride. It is the side-effect record for Riboflavin on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Riboflavin, this list is the first place to look.

  • Passing urine more often Additional detail

    “Orally, high doses of riboflavin can cause bright yellow urine. Furthermore, in one clinical study, one subject out of 28 reported polyuria two weeks after starting riboflavin 400 mg daily.”

    Riboflavin · Natural Medicines adverse-effect record, reported in myasthenia gravis.

    2 sources cited
    1. 1398. Schoenen J, Jacquy J, Lenaerts M. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology 1998;50:466-70. PubMed
    2. 3094. Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
  • Diarrhea Additional detail

    “Orally, riboflavin has been associated with rare diarrhea and dose-related nausea. In one clinical study, one subject out of 28 reported having diarrhea two weeks after starting riboflavin 400 mg daily.”

    Riboflavin · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 1398. Schoenen J, Jacquy J, Lenaerts M. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology 1998;50:466-70. PubMed
    2. 71483. MacLennan, S. C., Wade, F. M., Forrest, K. M., Ratanayake, P. D., Fagan, E., and Antony, J. High-dose riboflavin for migraine prophylaxis in children: a double-blind, randomized, placebo-controlled trial. J Child Neurol. 2008;23(11):1300-1304.
  • Nausea Additional detail

    “Orally, riboflavin is generally well tolerated.

    Most Common Adverse Effects:

    Orally: Dose-related nausea and urine discoloration.”

    Riboflavin · Natural Medicines adverse-effect record, reported in nausea and vomiting.

Everything above comes from the Natural Medicines adverse-effect record for Riboflavin — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Mechlorethamine Hydrochloride’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Mechlorethamine Hydrochloride column appears here.

Special populations

Riboflavin in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally and appropriately in dietary amounts. A tolerable upper intake level (UL) has not been established.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Riboflavin or Mechlorethamine Hydrochloride

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Riboflavin or Mechlorethamine Hydrochloride, 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 Mechlorethamine Hydrochloride

This page covers Riboflavin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mechlorethamine Hydrochloride page lists 10 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Acerola (moderate), Alpha-lipoic Acid (moderate), Coenzyme Q10 (moderate), Dimethylsulfoxide (dmso) (moderate) and Rose Hip (moderate).

By severity: 9 moderate · 1 minor.

From our pharmacist’s overview on the Mechlorethamine Hydrochloride page

“Mechlorethamine (Valchlor) is a chemotherapy gel applied to the skin for a form of lymphoma, and the 10 supplements on this page split into two groups. Seven are antioxidants, everyday products like vitamin C and turmeric, which in theory could blunt how well an alkylating chemotherapy drug works.”

Reviewed by 2 · Jul 18, 2026

Open the Mechlorethamine Hydrochloride interaction page

One more smart check

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

We hold 18,014 real supplement products containing Riboflavin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Riboflavin. Even though Riboflavin itself has no known interaction with Mechlorethamine Hydrochloride, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Riboflavin and Mechlorethamine Hydrochloride 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 Riboflavin
Top 1%

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

29 days ago today
Medication Mechlorethamine Hydrochloride
Steady interest

#1,633 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Riboflavin reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Riboflavin and Mechlorethamine Hydrochloride records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Riboflavin

What is Riboflavin?

  • Riboflavin deficiency
  • Migraine prevention
  • General energy and metabolism support
  • Healthy skin and eyes

Riboflavin (vitamin B2) is an essential nutrient your body needs to turn food into energy and to keep skin, eyes, and nerves healthy. It is generally very safe at typical doses, and the strongest evidence supports its use for treating deficiency, with some supportive (but not definitive) evidence for preventing migraines.

Vitamin (water-soluble B vitamin) · Tablets, capsules, softgels, multivitamins, B-complex products, fortified foods

An interaction check asks whether these two react with each other — it does not ask whether Riboflavin is a good idea for someone in your situation. Here is what our Riboflavin record says about it on its own.

Riboflavin: dosing

There is a recommended daily intake for riboflavin as a nutrient, and most people meet it through a normal diet. Do not assume that more is better.

From our Riboflavin monograph — the full record covers uses, side effects and every documented interaction.

Read the full Riboflavin monograph & all interactions
Medication

About Mechlorethamine Topical

What Is Mechlorethamine Topical Used For?

Brand name: Valchlor

Valchlor (mechlorethamine gel applied to the skin) is approved to treat Stage IA and IB mycosis fungoides-type cutaneous T-cell lymphoma — a slow-growing cancer that primarily affects the skin. It is used in patients who have already received at least one prior skin-directed treatment.

Most-Reported Side Effects for Mechlorethamine Hydrochloride

From FAERS, the FDA’s public side-effect reporting system (2,244 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Pruritus 322 reports
Application site pruritus 224 reports
Application site erythema 220 reports
Application site pain 218 reports
Erythema 213 reports
See full Mechlorethamine Topical drug information
Keep checking

Other Drugs & Riboflavin

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

0Major
20Moderate
0Minor
2,809No known interaction
20 Moderate 2,809 No interaction
Moderate

20 interactions

No interaction 2,809 drugs checked — show the list

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

Showing the 60 most looked-up of 2,809 medications checked with no known interaction — see the full Riboflavin list.

See the full Riboflavin interactions page
See every supplement checked against Mechlorethamine Hydrochloride, ranked by severity
Evidence & sources

Riboflavin References

The 5 references that drive our Riboflavin monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Schoenen J, Jacquy J, Lenaerts M. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology 1998;50:466-70. PubMed
  2. Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
  3. Leeson LJ, Weidenheimer JF. Stability of tetracycline and riboflavin. J Pharm Sci. 1969;58(3):355-7. PubMed
  4. MacLennan, S. C., Wade, F. M., Forrest, K. M., Ratanayake, P. D., Fagan, E., and Antony, J. High-dose riboflavin for migraine prophylaxis in children: a double-blind, randomized, placebo-controlled trial. J Child Neurol. 2008;23(11):1300-1304.
  5. Dietary reference intakes (DRIs): estimated average requirements. Food and Nutrition Board, Institute of Medicine, National Academics. https://www.nal.usda.gov/sites/default/files/fnic_uploads//recommended_intakes_individuals.pdf Accessed July 24, 2017.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Riboflavin and Mechlorethamine Hydrochloride Together: Common Questions

Is it safe to take Riboflavin with Mechlorethamine Hydrochloride?
We do not list a known interaction between Riboflavin and Mechlorethamine Hydrochloride. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Riboflavin and Mechlorethamine Hydrochloride combination checked?
Interactions in our licensed database are recorded against drug classes. Mechlorethamine Hydrochloride is filed under 2 classifications, and Riboflavin has documented interactions with 1 drug class — none of Mechlorethamine Hydrochloride's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Riboflavin interact with any other medications?
Yes. Riboflavin has 20 documented drug interactions in our database — Mechlorethamine Hydrochloride is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Mechlorethamine Hydrochloride interact with any supplements?
Yes. Mechlorethamine Hydrochloride has documented interactions with 10 supplements in our database — Riboflavin is not one of them. The Mechlorethamine Hydrochloride interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Riboflavin monograph Uses, safety profile, and every drug interaction in one place Mechlorethamine Topical drug information The full plain-English guide to this medication Mechlorethamine Hydrochloride supplement interactions Every supplement checked against Mechlorethamine Hydrochloride, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Mechlorethamine Hydrochloride and Riboflavin?

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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.