Applies to tryptophan: oral capsule.

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:

• unusual tiredness;

• 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

• uneven heartbeat.

Common side effects may include:

• feeling drowsy or light-headed;

• dry mouth, heartburn, burping, gas;

• stomach pain, nausea, vomiting, diarrhea;

• weakness, lack of coordination;

• blurred vision;

• headache; or

• sexual problems.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.