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Methylene blue Side Effects

For the Consumer

Applies to methylene blue: intravenous solution

Along with its needed effects, methylene blue may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking methylene blue:

Incidence not known
  • Agitation
  • bluish-colored lips, fingernails, or palms
  • confusion
  • cough
  • dark urine
  • diarrhea
  • difficulty breathing
  • difficulty swallowing
  • dizziness or lightheadedness
  • fast heartbeat
  • fever
  • headache
  • hives or welts, itching, or skin rash
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • overactive reflexes
  • pale skin
  • poor coordination
  • rapid heart rate
  • redness of the skin
  • restlessness
  • shivering
  • sore throat
  • sweating
  • talking or acting with excitement you cannot control
  • tightness in the chest
  • trembling or shaking
  • twitching
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Get emergency help immediately if any of the following symptoms of overdose occur while taking methylene blue:

Symptoms of overdose
  • Abdominal or stomach pain
  • bigger, dilated, or enlarged pupils (black part of the eye)
  • blue staining of the urine, skin, and mucous membranes
  • bluish-colored lips, fingernails, or palms
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • confusion
  • dark urine
  • difficulty breathing
  • dizziness or lightheadedness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • fear
  • fever
  • headache
  • increased sensitivity of the eyes to light
  • nausea
  • pale skin
  • rapid heart rate
  • rapid shallow breathing
  • shakiness in the legs, arms, hands, or feet
  • sore throat
  • tightness in the chest
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vomiting

Some side effects of methylene blue may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Change in taste
  • changes in skin color
  • feeling hot or cold
  • increased sweating
  • loss of taste
  • muscle or joint pain
  • pain at the infusion site
  • pain in the arms or legs
Less common
  • Back pain
  • bruising
  • chills
  • general feeling of discomfort or illness
  • large, flat, blue or purplish patches in the skin
  • loss of appetite
  • muscle aches and pains
  • muscle spasm
  • runny nose
  • trouble sleeping

For Healthcare Professionals

Applies to methylene blue: compounding powder, injectable solution, intravenous solution, oral tablet


Common (1% to 10%): Chest pain, chest discomfort, presyncope, syncope
Frequency not reported: Cardiac arrhythmia, tachycardia, hypertension, hypotension, palpitations[Ref]


Common (1% to 10%): Ecchymosis
Frequency not reported: Hemolytic anemia, hemolysis, methemoglobinemia, hemoglobin decreased, hyperbilirubinemia (in infants only)[Ref]


Frequency not reported: Anaphylaxis[Ref]


Common (1% to 10%): Influenza-like illness[Ref]


Common (1% to 10%): Injection site pain, injection site discomfort
Frequency not reported: Infusion site extravasation, infusion site induration, infusion site pruritus, infusion site swelling, infusion site urticaria, peripheral swelling[Ref]


Very common (10% or more): Pain in extremity (84%)
Common (1% to 10%): Musculoskeletal pain, back pain, muscle spasms, chills, arthralgia
Frequency not reported: Serotonin syndrome, myalgia[Ref]


Frequency not reported: Mydriasis, eye pruritus, ocular hyperemia, vision blurred[Ref]


Common (1% to 10%): Decreased appetite, limb discomfort
Frequency not reported: Local tissue necrosis at the injection site[Ref]


Common (1% to 10%): Anxiety
Frequency not reported: Confusional state, agitation[Ref]


Very common (10% or more): Chromaturia (blue-green) (74%)
Frequency not reported: Dysuria[Ref]


Frequency not reported: Elevated liver enzymes[Ref]


Common (1% to 10%): Dyspnea
Frequency not reported: Dyspnea, tachypnea, hypoxia, nasal congestion, rhinorrhea, sneezing[Ref]


Very common (10% or more): Feeling hot (17%), fever
Common (1% to 10%): Feeling cold, discomfort, catheter site pain
Frequency not reported: Genotoxicity, fever, lack of effectiveness, interference with in-vivo monitoring devices, interference with laboratory tests[Ref]

Nervous system

Very common (10% or more): Dysgeusia (20%), dizziness (16%), headache (10%), paresthesia
Common (1% to 10%): Headache, paresthesia oral, dizziness postural
Frequency not reported: Serotonin syndrome (with concomitant use of serotonergic drugs), tremor, aphasia, tremor, aphasia[Ref]


Very common (10% or more): Skin discoloration (blue) (13%), hyperhidrosis (13%), sweating
Common (1% to 10%): Pallor, contact dermatitis, pruritus, cold sweat, erythema
Frequency not reported: Urticaria, necrotic ulcer, papule, phototoxicity, rash (blue macules, severe burning pain)[Ref]


Very common (10% or more): Nausea (13%)
Common (1% to 10%): Vomiting, abdominal pain, diarrhea, hypoesthesia oral, oral discomfort
Frequency not reported: Feces discoloration (blue-green), dry mouth, flatulence, glossodynia, tongue eruption, thirst, oropharyngeal pain, blue colored saliva[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Provayblue (methylene blue)." American Regent Laboratories Inc, Shirley, NY.

4. "Product Information. Methylene Blue (methylene blue)." American Regent Laboratories Inc, Shirley, NY.

Some side effects of methylene blue may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.