Tryptophan - I felt a burning in my esophagus one hour after taking the 500 mg pill. I fell asleep?

Here is a list of side effects of L-tryptophan. While heartburn is considered a less serious side effect, burning pain might be more serious. Stop taking the tryptophan and see your doctor if you are concerned.

L-tryptophan side effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

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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.
There have been no published cases of EMS within the last several years, but you should be aware of the symptoms. Call your doctor at once if you have any of the following:

*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);
*breathing difficulty; or
*uneven heartbeat.

Less serious side effects may include:

*dry mouth, heartburn, burping, gas;
*nausea, vomiting, diarrhea;
*feeling drowsy or light-headed;
*blurred vision;
*weakness, lack of coordination;
*headache; or
*lost appetite.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

You will find more information at http://www.drugs.com/mtm/l-tryptophan.html