Drugs A - Z

Methylene Blue Oral tablet

It is a dye that is used in certain diagnostic procedures.

Generic Name: methylene blue

Brand Names: Urolene Blue

There is an FDA Alert for this drug. Click here to view it.

Special Alerts:

[UPDATED 10/21/2011] FDA updated healthcare professionals and the public on the potential drug interaction between methylene blue and serotonergic psychiatric medications. Most cases from the FDA's Adverse Event Reporting System (AERS) of serotonin syndrome in patients given serotonergic psychiatric medications and methylene blue occurred in the context of parathyroid surgery, which involved the intravenous administration of methylene blue as a visualizing agent. Methylene blue doses ranged from 1 mg/kg to 8 mg/kg.

Because methylene blue is not an FDA-approved drug at this time, and limited data exist regarding its use in various settings, it is not known whether there is a risk of serotonin syndrome in patients taking serotonergic psychiatric medications who are given methylene blue by other routes (e.g., orally or by local tissue injection) or at intravenous doses lower than 1 mg/kg.

In addition, not all serotonergic psychiatric drugs have an equal capacity to cause serotonin syndrome with methylene blue. The cases of serotonin syndrome with methylene blue occurred in patients taking specific serotonergic psychiatric drugs, namely a selective serotonin reuptake inhibitor (SSRI), a serotonin norepinephrine reuptake inhibitor (SNRI), or clomipramine. It is unclear at this time whether intravenous methylene blue administration in patients receiving other psychiatric drugs with lesser degrees of serotonergic activity poses a comparable risk.

FDA will update the public when new information is available. For more information visit the FDA website at: [Web] and [Web].

[Posted 07/26/2011] ISSUE: FDA has received reports of serious central nervous system (CNS) reactions when the drug methylene blue is given to patients taking psychiatric medications that work through the serotonin system of the brain (serotonergic psychiatric medications). A list of the serotonergic psychiatric medications that can interact with methylene blue can be found in the Drug Safety Communication. Safety information about this potential drug interaction and important drug usage recommendations for emergency and non-emergency situations are being added to the drug labels for serotonergic psychiatric medications.

BACKGROUND: Methylene blue is used to treat methemoglobinemia, vasoplegic syndrome, ifosfamide-induced encephalopathy, and cyanide poisoning. It is also used as a dye in therapeutic and diagnostic applications. Methylene blue is a potent, reversible monoamine oxidase inhibitor (MAOI). Although the exact mechanism of this drug interaction is unknown, methylene blue inhibits the action of monoamine oxidase A — an enzyme responsible for breaking down serotonin in the brain. It is believed that when methylene blue is given to patients taking serotonergic psychiatric medications, high levels of serotonin can build up in the brain, causing toxicity. This is referred to as Serotonin Syndrome — signs and symptoms include mental changes (confusion, hyperactivity, memory problems), muscle twitching, excessive sweating, shivering or shaking, diarrhea, trouble with coordination and/or fever.

RECOMMENDATION: Methylene blue should generally not be given to patients taking serotonergic drugs. However, there are some conditions that may be life-threatening or require urgent treatment with methylene blue such as when it is used in the emergency treatment of methemoglobinemia, ifosfamide-induced encephalopathy, or cyanide poisoning.

Patients should not stop taking their serotonergic psychiatric medicine without first talking to a healthcare professional. Read the Drug Safety Communication at: [Web] for other specific recommendations for Healthcare Professionals and for Patients. For more information visit the FDA website at: [Web] and [Web].

What is this medicine?

METHYLENE BLUE (METH uh leen bloo) is a dye that is used in certain diagnostic procedures.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
  • cyanide poisoning
  • glucose-6-phosphate dehydrogenase (G6PD) deficiency
  • kidney disease
  • an unusual or allergic reaction to methylene blue, phenothiazines, thiazide diuretics, other medicines, foods, dyes, or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

How should I use this medicine?

Take this medicine by mouth with a full glass of water. Follow the directions on the prescription label. Take after meals. Take your doses at regular intervals. Do not take your medicine more often than directed.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
  • bupropion
  • certain medicines for depression or anxiety
  • clomipramine
  • doxepin
  • duloxetine
  • fluoxetine
  • MAOIs like Marplan, Nardil, and Parnate
  • milnacipran
  • mirtazapine
  • rasagiline
  • selegiline
  • St. John's wort
  • trazodone
  • tryptophan

What should I watch for while using this medicine?

Visit your doctor or health care professional for regular checks on your progress.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
  • bladder irritation
  • fever

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • blue-green coloration of urine and stools
  • diarrhea
  • nausea, vomiting
  • skin discoloration

Where should I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from moisture and light. Throw away any unused medicine after the expiration date.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.


Last Updated: November 19, 2012
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