What are the side effects of methylene blue?

Methylene blue can make the urine or stools look blue or green, which is a normal, typically harmless side effect. Another side effect is that the medicine may affect the results of some medical tests. It can cause an allergic response, such as hives, breathing problems or a swollen face, mouth, tongue or throat. Other side effects include: serious vomiting, nausea or stomach ache; blue or pale skin, lips or fingernails; chest pain, back pain, leg pain or pain behind the breast bone; anxiety; headaches or dizziness; high fever or chills, severe sweating, fast or pounding heartbeat or breathing problems; or confusion, trembling, feeling faint or unusual tiredness or weakness. Less severe side effects include: mild irritation of the bladder; mild vomiting, nausea, diarrhea or upset stomach; increased sweating; or painful urination or increased need to urinate.

Continue Learning about Diagnostic Agent

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.