Methylene Blue Side Effects

Medically reviewed by Drugs.com. Last updated on Dec 14, 2023.

Applies to methylene blue: intravenous solution.

Important warnings This medicine can cause some serious health issues

Intravenous route (solution)

Warning: Serotonin Syndrome With Concomitant Use of Serotonergic Drugs And Opioids.

Methylene blue may cause serious or fatal serotonergic syndrome when used in combination with serotonergic drugs.

Avoid concomitant use of methylene blue with selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and monoamine oxidase inhibitors.

Common side effects of methylene blue

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 side effects

• arm or leg pain
• 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

Less common side effects

• 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

Serious side effects of methylene blue

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
• chest tightness
• 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
• 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

• 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
• chest tightness
• 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
• stomach pain
• unusual bleeding or bruising
• unusual tiredness or weakness
• vomiting

For healthcare professionals

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

Cardiovascular adverse events

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

Hematologic

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

Hypersensitivity

• Frequency not reported: Anaphylaxis^[Ref]

Immunologic

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

Local

• 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]

Musculoskeletal

• 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]

Ocular

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

Metabolic

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

Psychiatric

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

Genitourinary

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

Hepatic

• Frequency not reported: Elevated liver enzymes^[Ref]

Respiratory

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

Other

• 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]

Dermatologic

• 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]

Gastrointestinal

• 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]

Further information

Methylene blue side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

Medical Disclaimer