What are the side effects of tryptophan?

Tryptophan (also called L-tryptophan) can cause a number of side effects, including heartburn, stomach pain, gas, nausea, vomiting, diarrhea, headache, lightheadedness, dry mouth, blurred vision, loss of coordination, drowsiness and loss of appetite.

Be especially on guard for side effects associated with eosinophilia-myalgia syndrome, a serious, potentially fatal condition that has been seen only in people taking tryptophan. These include:
  • extreme muscle pain
  • severe fatigue
  • nerve abnormalities (loss of reflexes, numbness, weakness, tingling, burning pain especially at night)
  • shaking or twitching in your muscles
  • swelling anywhere, but especially in your hands or feet
  • a rash or patches of hard, dry skin
  • low fever
  • hair loss
  • irregular heartbeat
  • shortness of breath or coughing
Seek medical care right away if you experience any of these symptoms.

In 1989, more than 1,500 people in the United States came down with eosinophilia-myalgia syndrome, and 37 died. It is possible that the outbreak was caused by impurities in the product of a single manufacturer rather than by tryptophan itself, but this has not been proved. In 1990, tryptophan was temporarily banned, and although it is once again available, it is still considered possibly unsafe.

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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.