What Happens If You Take Too Much Methylene Blue? Overdose Signs

With methylene blue, more is not better, and too much can cause real harm. Drugs.com lists overdose symptoms as vomiting, stomach pain, chest tightness, trouble breathing, a racing heart, tremor, confusion, and blue-colored skin or lips (not to be confused with the normal blue-green urine tint). If you think you or someone else has taken too much, call Poison Control at 1-800-222-1222 (U.S.) immediately or seek emergency care.

• Dose matters more than anything else. The StatPearls clinical reference puts the no-adverse-effect threshold at under 2 mg per kg of body weight, with real toxicity beginning around 7 mg per kg. A labeled supplement serving sits far below that line.
• The most realistic risk is a drug interaction, not raw quantity. An FDA drug safety communication warns that methylene blue combined with SSRIs, SNRIs, or other serotonergic medications can trigger serotonin syndrome, even at doses well below the toxicity range.
• Never stack multiple methylene blue products. Taking more than one Nutricel formula at once, or adding a supplement on top of a prescription IV dose, is the easiest way to go over a safe total without noticing.

Important: An FDA drug safety communication (2011) warns about serotonin syndrome when methylene blue is combined with serotonergic medications, including SSRIs and MAOIs. Review the full adverse medications list before use.

More is not better because the dose response is not a straight line. Gonzalez-Lima and Auchter (Frontiers in Cellular Neuroscience, 2015) describe it as hormetic: in lab studies, low doses supported mitochondrial function and much higher doses worked against it. That is why we keep our formulas in the single-digit to low-double-digit milligram range per capsule, and why the recommended dosing protocol exists in the first place.

The StatPearls clinical reference reports no recorded adverse effects at therapeutic doses under 2 mg per kg of body weight. It links single doses of 3 mg per kg or more to low blood pressure, wheezing, and reduced oxygenation, and cumulative doses of 7 mg per kg or more to real toxicity.

According to Drugs.com, overdose symptoms can include vomiting, stomach pain, chest pain or tightness, wheezing, trouble breathing, feeling like you might pass out, a fast heart rate, anxiety, confusion, tremor, dilated pupils, blue-colored skin or lips, numbness, or tingling. We grouped them below by rough severity. Any of them is a reason to stop taking it and pay close attention.

Do not mix up two kinds of blue. Blue or green urine is an expected effect of methylene blue at normal doses, and Drugs.com does not list it as an overdose sign. Blue skin or lips is on the Drugs.com overdose list and is a reason to get help.

For most people taking a supplement, the bigger risk is not the amount. It is taking methylene blue alongside a medication that raises serotonin. The FDA explains that methylene blue blocks monoamine oxidase A (MAO-A), the enzyme that breaks down serotonin, so pairing it with a serotonergic drug can push serotonin too high, even at doses well below the toxicity numbers above.

The FDA issued a drug safety communication in October 2011 warning that methylene blue combined with SSRIs, SNRIs, tricyclic antidepressants, MAOIs, or other serotonergic psychiatric medications can trigger serotonin syndrome, in some reported cases fatal. The cases FDA reviewed largely involved intravenous methylene blue during surgery at doses between 1 and 8 mg per kg, alongside an SSRI, SNRI, or clomipramine.

If you take methylene blue while on a serotonergic medication, watch for the signs the FDA lists, such as confusion, muscle twitching, heavy sweating, shaking, and fever. Our full drug interactions guide covers named drug classes and washout timing in more depth.

Yes, at very high doses methylene blue can cause the same blood problem it is used to fix. It is FDA-approved for methemoglobinemia, a condition where blood cannot carry oxygen properly, and at normal doses it turns methemoglobin back into working hemoglobin. But StatPearls notes that excessive doses above 7 mg per kg can flip this mechanism: instead of reducing methemoglobin, methylene blue starts directly oxidizing hemoglobin and can induce the very condition it is meant to treat, with methemoglobin levels documented up to 7% at that threshold.

At even higher doses, above roughly 15 mg per kg, the same clinical literature associates methylene blue with hemolysis (red blood cell breakdown), particularly in neonates, and at 20 mg per kg or more, severe intravascular hemolysis, hyperbilirubinemia, and death have been reported. These figures come from IV dosing in hospitals and are far above anything you could reach with a labeled oral serving. We include them because they explain why dosing guidelines are conservative and why we tell people not to stack methylene blue products.

• Call Poison Control at 1-800-222-1222 (U.S.) right away, or go to an emergency room if symptoms are severe (trouble breathing, passing out, blue-colored skin or lips).
• Have the product and label on hand. Drugs.com recommends being ready to tell or show what was taken, how much, and when.
• Do not wait for symptoms to worsen. Mild nausea or a headache can come first, before the more serious symptoms.
• Mention any medications you take. If you are on an SSRI, SNRI, MAOI, or other serotonergic drug, say so right away, because it changes what the care team looks for.

Do not take methylene blue if you are currently using:

• SSRIs, SNRIs, or MAOIs (the FDA warns of serotonin syndrome)
• Any other serotonergic medication

Review the full adverse medications list and consult your healthcare provider before starting methylene blue in any form.

Every Nutricel product uses USP-grade methylene blue and is made in an GMP certified facility in the United States, and our capsules are third-party tested by independent labs. We keep each formula at the low end of the range described above.

Blue Boost is our core formula: 12 mg of USP-grade methylene blue per capsule.

Blue Immune combines methylene blue with copper, magnesium, NAC, grass-fed beef liver, and camu camu for fatigue and cellular energy support.

Blue Shroom pairs a lower 7 mg methylene blue dose with six organic mushroom extracts so the methylene blue amount stays lower.

Blue Renew is built around GlyNAC with collagen and creatine, aimed at longevity and brain function as you age.

Blue Remove combines zeolite, curcumin, and nattokinase, aimed at circulation and the body's normal inflammatory response.

Blue Liquid is USP-grade methylene blue in a dropper bottle (10 mg per mL), for people who want to measure small amounts themselves.

Sam Carlson, Marketing Developer at Nutricel

Sam is a marketing developer at Nutricel who writes the Nutricel Insights series to help our customers understand methylene blue and make informed choices, translating the published research into plain language. Sam is not a medical professional, and these articles are intended as education rather than medical advice. Every figure in this piece is tied to the sources referenced above, and you should always speak with your healthcare provider before starting any supplement.