Herb & supplement monograph

Methylene Blue Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Methylene Blue interacts with medications. The heart of this page is the interaction list — every drug Methylene Blue is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Methylene Blue is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Methylene Blue Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, Methylene Blue drug interactions carry a moderate overall risk for most people, with the greatest concern for anyone taking a medication that raises serotonin. Every interaction on record is rated moderate in severity, with none classed as major or minor.

Interactions deserving the most attention

The concern that stands out most is with serotonergic drugs. Methylene blue blocks an enzyme the body uses to break down serotonin, and when given by vein or into the lungs it has caused serotonin syndrome, including some reported deaths, in people taking these medications. This has not been reported with oral methylene blue, but the combination is still best avoided. Anticholinergic drugs may also add to side effects such as fever, dry mouth, and dilated pupils, based on a single report in a critically ill patient.

What the rest of the list means

A long list of interacting medications does not mean each pairing is well proven. Here, the list mostly reflects two broad drug classes rather than hundreds of separately studied combinations, and the documentation rests largely on case reports and a known enzyme effect rather than well-controlled human studies.

Check your medications against Methylene Blue

Based on HelloPharmacist’s Methylene Blue interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Methylene Blue

315 medications have a known interaction with Methylene Blue, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Methylene Blue using our pharmacist-reviewed interaction data.

AI summaries are generated from our Methylene Blue interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Methylene Blue combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Methylene Blue affects

Every type of medication (drug category) Methylene Blue is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Methylene Blue interacts with

Anticholinergic DrugsSerotonergic Drugs

Anticholinergic Drugs

Concomitant use may increase anticholinergic effects and adverse effects. In a case report, a critically-ill male in his mid-60s developed a toxicological process attributed to anticholinergic syndrome following treatment with methylene blue for vasoplegia. Symptoms included anhidrosis, fever, lactic acidosis, mucosal dryness, and pupil dilation. Potential exacerbating factors included renal failure and use of fentanyl intra-operatively.

Likelihood Possible Evidence D

Serotonergic Drugs

Combining serotonergic drugs with methylene blue can cause additive serotonergic effects, including serotonin syndrome. Methylene blue inhibits monoamine oxidase A. Intravenous or intrapulmonary use has resulted in serotonin syndrome, including reported fatalities, in patients taking some serotonergic drugs. This effect has not been reported with oral methylene blue. However, tell patients to avoid taking methylene blue with serotonergic drugs.

Likelihood Possible Evidence C

Monograph

Methylene Blue: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Methylene blue is a synthetic dye that is an FDA-approved prescription medicine for a rare blood disorder called methemoglobinemia, and it is also used as a diagnostic dye. Its popular use as a supplement for energy, brain health, or anti-aging is not well supported by solid human evidence, and it can cause serious side effects. Talk to a pharmacist or doctor before using it, and never take non-pharmaceutical or industrial-grade products.

Part used: Synthetic chemical compound (not derived from a plant)
Common forms: Prescription injection, oral tablets, and compounded liquid or capsule supplements

People commonly use it for

Methemoglobinemia (a blood disorder)
Claimed energy or mental focus support
Anti-aging or longevity claims
Antimicrobial or antimalarial uses (historical)
Dye for medical and lab procedures

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

It is a real drug with real risks; medical-grade forms need supervision and it should not be self-dosed casually.

PregnancyLikely Unsafe

Likely Unsafe when prescription methylene blue is used intra-amniotically. When provided during the second trimester, methylene blue has caused fetal...

Read the full pregnancy detail

BreastfeedingPossibly Unsafe

Possibly Unsafe when prescription methylene blue products are administered to patients who are lactating. Breast-feeding should be discontinued during...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Methylene blue is a bright blue, man-made chemical dye. It is not an herb or plant product, even though it is sometimes sold as a dietary supplement. It was first created in the late 1800s and has a long history in medicine and laboratory science.

In hospitals, methylene blue is an FDA-approved prescription medicine used to treat a blood condition called methemoglobinemia, where the blood cannot carry oxygen properly. It is also used as a dye to stain tissues and help doctors see certain structures during medical tests and surgery.

More recently, methylene blue has become popular online as a supplement, with sellers claiming it can boost energy, sharpen thinking, or slow aging. These uses are very different from its approved medical uses, and the supplement versions are not tightly regulated.

How it works

Methylene blue can accept and give up electrons, which lets it take part in reactions inside cells. In methemoglobinemia, it helps convert an abnormal form of hemoglobin back to normal so the blood can carry oxygen again.

Supporters of its supplement use point to laboratory studies suggesting it may affect the mitochondria, the tiny "powerhouses" inside cells, and may act as an antioxidant at low amounts. Some research also looks at how it affects brain chemicals.

It is important to know that most of these effects come from test tube and animal studies. What happens in a lab does not always match what happens in the human body, and the doses used in research may differ greatly from what people take on their own.

Effectiveness

Does Methylene Blue work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 21 uses evaluated

21 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Methylene Blue, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 21 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Age-related cognitive decline