Tryptophan Side Effects
Medically reviewed by Drugs.com. Last updated on Jul 7, 2022.
Applies to tryptophan: oral capsule
Follow all directions on the product label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Although not all side effects are known, L-tryptophan is thought to be possibly unsafe. Be sure to use this product only if you have obtained it from a safe and reputable source.
In 1989, a life-threatening condition called eosinophilia-myalgia syndrome (EMS) occurred in many people using L-tryptophan and some died from the condition. All of these people had taken L-tryptophan distributed by a company in Japan. This L-tryptophan was found to contain trace levels of impure ingredients. Since that time, the FDA has limited the availability of L-tryptophan in the U.S. However, the increased use of the Internet has made many dietary supplements available from non-U.S. sources.
Although there have been no published cases of EMS within the last several years, you should be aware of the symptoms. Stop using L-tryptophan and seek emergency medical help if you have signs of EMS:
severe muscle pain (most often in the shoulders, back, or legs);
weakness, numbness, tingling, or burning pain (especially at night);
tremors or twitching muscle movements;
swelling in any part of your body;
skin changes (dryness, yellowing, hardening, rash, hair loss);
breathing difficulty; or
Common side effects may include:
feeling drowsy or light-headed;
dry mouth, heartburn, burping, gas;
stomach pain, nausea, vomiting, diarrhea;
weakness, lack of coordination;
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
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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.