Possible side effects of L-tryptophan include loss of appetite, dry mouth and drowsiness. Nausea, headache or dizziness are other possible side effects, according to Drugs.com.
More possible side effects of L-tryptophan include lightheadedness, blurred vision, sexual problems and weakness. Women who are pregnant or nursing should not take L-tryptophan. L-tryptophan may worsen a white blood cell disorder called eosinophilia. People with kidney or liver disease should avoid L-tryptophan unless otherwise directed by a physician, according to WebMD.
It is possible to overdose on L-tryptophan. Signs of an overdose include sweating, restlessness, trembling and shaking. Other signs of an overdose include diarrhea, agitation, confusion and a lack of coordination. Additional signs of an overdose include uncontrollable excitement, twitching, fever, overactive reflexes and vomiting. If signs of an overdose occur, it is important to seek medical attention immediately, notes Drugs.com.
L-tryptophan has been linked to numerous cases of eosinophilia-myalgia syndrome. L-tryptophan has also been linked to some deaths. Symptoms of EMS include intense muscle or nerve pain, baldness, skin changes and fatigue. Some people with EMS may experience swelling that affects the heart, liver, lungs, joints or connective tissue. Evidence suggests that past cases of EMS may have been due to contaminated L-tryptophan products, states WebMD.