L-tryptophan

L-tryptophan is an amino acid that comes from plant or animal sources. It is called an "essential" amino acid because the body cannot make it. L-tryptophan is important for the functions of many organs in the body. When you take L-tryptophan, your body absorbs it and changes it into a hormone called serotonin. Serotonin sends signals between your nerve cells and also narrows (constricts) blood vessels. The amount of serotonin in the brain can affect your mood.

L-tryptophan has been used in alternative medicine as a possibly effective treatment for symptoms of premenstrual dysphoric disorder syndrome (like mood swings and irritability), and to help people quit smoking.

L-tryptophan has also been used to treat facial pain, relieve bruxism (tooth grinding), and improve athletic performance. However, research has shown that L-tryptophan may not be effective for these conditions.

Other uses that have not been proven by research include treating sleep problems (insomnia), anxiety, depression, and attention deficit hyperactivity disorder (ADHD).

It is not clear if L-tryptophan is effective for any medical condition. The FDA has not approved its medicinal use. L-tryptophan should not be used instead of medication prescribed by your doctor.

L-tryptophan is often sold as an herbal supplement. There are no regulated manufacturing standards for many herbal products, and some supplements have been found to contain toxic metals or other drugs. Herbal/health supplements should be bought from a trustworthy source to reduce the risk of contamination.

It may be dangerous to buy L-tryptophan online or from vendors outside of the United States. The manufacture, sale, and distribution of L-tryptophan outside the U.S. do not follow FDA regulations for the safe use of this medication.

L-tryptophan may also be used for purposes not listed in this product guide.

When thinking about using herbal supplements, ask your doctor for advice. You might also want to talk to someone who is trained in herbal/health supplements.

If you decide to use L-tryptophan, follow the instructions on the package or the advice from your doctor, pharmacist, or other healthcare provider. Do not take more of this product than what is recommended on the label.

Call your doctor if the condition you are treating with L-tryptophan does not get better, or if it worsens while using this product.

Store at room temperature, away from moisture and heat.

Follow all instructions on the product label and package. Inform each of your healthcare providers about all your medical conditions, allergies, and all medicines you are taking.

You should not use this product if you are allergic to tryptophan.

Ask a doctor, pharmacist, or other healthcare provider if it is safe for you to use this product if you have:

• liver disease;
• kidney disease;
• eosinophilia (high levels of a certain type of white blood cells); or
• a muscle disorder (such as fibromyalgia).

L-tryptophan is considered likely unsafe to use during pregnancy. Do not use this product without medical advice if you are pregnant.

It is not known whether L-tryptophan passes into breast milk or if it could harm a nursing baby. Do not use this product without medical advice if you are breast-feeding a baby.

Do not give any herbal/health supplement to a child without medical advice.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Although not all side effects are known, L-tryptophan is thought to possibly be unsafe. Be sure to use this product only if you have obtained it from a safe and reputable source.

In 1989, a serious condition called eosinophilia-myalgia syndrome (EMS) occurred in many people using L-tryptophan, and some died from this 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 then, 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 in recent 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);
• difficulty breathing; or
• uneven heartbeat.

Common side effects of L-tryptophan 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. You may report side effects to the FDA at 1-800-FDA-1088.

Skip the missed dose if it is nearly time for your next dose. Do not take extra L-tryptophan to compensate for the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Avoid taking an herbal supplement containing St. John's wort at the same time you are taking L-tryptophan.

Avoid using L-tryptophan together with other herbal/health supplements that can also cause drowsiness, including 5-hydroxytryptophan (5-HTP), calamus, California poppy, catnip, hops, Jamaican dogwood, kava, St. John's wort, skullcap, valerian, or yerba mansa.

Avoid using L-tryptophan together with other herbal/health supplements that can raise your serotonin levels. This includes 5-HTP, Hawaiian baby woodrose, and S-adenosylmethionine (SAMe).

L-tryptophan may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Taking L-tryptophan with other medications that make you feel sleepy can increase this effect. Speak with your doctor before using L-tryptophan along with a sleeping pill, narcotic pain medicine, muscle relaxer, or medication for anxiety, depression, or seizures.

Do not take L-tryptophan without medical advice if you are taking any of the following medications:

• tramadol (Ultram, Ultracet);
• a cough medicine that contains dextromethorphan (Delsym, Robitussin DM, and others);
• an MAO inhibitor such as isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others;
• medication to treat mental illness such as chlorpromazine (Thorazine), fluphenazine (Prolixin), thioridazine (Mellaril), and others;
• a narcotic medicine such as meperidine (Demerol) or pentazocine (Talwin); or
• a sedative such as diazepam (Valium), clonazepam (Klonopin), lorazepam (Ativan), and others.

This list is not complete. Other drugs may interact with L-tryptophan, including prescription and over-the-counter medications, vitamins, and herbal products. Not all possible interactions are included in this product guide.