L-tryptophan is an essential amino acid that helps the body perform many functions, including the production of serotonin. Serotonin is a brain chemical that influences mood.

Although there is some evidence that L-tryptophan may help with certain conditions such as anxiety or sleep disorders, more research is needed to determine whether or not taking L-tryptophan supplements is effective.

This article investigates the safety and effectiveness of L-tryptophan supplements.

What exactly is L-tryptophan?

L-tryptophan, also known as tryptophan, is an essential amino acid that aids in the production of serotonin. Serotonin is a hormone found throughout the body, including the brain. Serotonin in the brain regulates a person’s mood, anxiety, and happiness levels.

L-tryptophan can also be purchased as a supplement.

Potential advantage
Because L-tryptophan aids in the production of serotonin in the brain, some experts believe it may aid in the treatment of conditions such as anxiety and sleep disorders. There is some evidence that it can be used for these purposes.


In one small study of 25 young adults, the researchers discovered that changing the participants’ diets to include more L-tryptophan caused positive changes in their mood. It also reduced anxiety and depression symptoms.

The researchers discovered a link between low levels of L-tryptophan and depression and anxiety symptoms in rodents in a 2016 reviewTrusted Source.

In humans, the authors noted that those most likely to be affected are those who have risk factors for depression. It is possible that higher tryptophan levels will benefit vulnerable populations.


In a 2016 study of young people undergoing drug detox, the researchers discovered that the participants experienced minimal or no improvement in mental symptoms associated with their detox process.

They did note, however, that L-tryptophan was effective in helping participants sleep during the detox process. The researchers also stated that more research is needed to determine how effective it is.

Dysphoric premenstrual syndrome
L-tryptophan may help alleviate pain associated with premenstrual dysphoric disorder, according to an older studyTrusted Source. The study also discovered that people who ate little or no amino acid had worse symptoms of premenstrual syndrome (PMS).

Tolerance to pain

The researchers examined how L-tryptophan levels affect a person’s pain tolerance in a 2017 studyTrusted Source. The study discovered that higher levels of this amino acid reduced pain.

Adverse effects
When consumed as part of a regular diet, L-tryptophan is safe. When taken as a supplement, a person may experience minor side effects.

One study found that

According to a reliable source, some common but minor side effects include:

  1. nausea
  2. tremor

sleepiness (in those not taking it for sleep disorders) (in those not taking it for sleep disorders)

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More Dangers

Although it is uncommon, serotonin syndrome can occur if a person takes multiple medications for depression or anxiety at the same time.

Though uncommon, serotonin syndrome is most likely to occur when an L-tryptophan supplement is combined with medications that alter serotonin levels, such as antidepressants.

Serotonin syndrome symptoms may include:

delirium hyperthermia coma involuntary twitching or jerking
Researchers temporarily linked tryptophan supplements to eosinophilia myalgia syndrome in 1989Trusted Source (EMS). EMS symptoms include incapacitating muscle pain and a high peripheral eosinophil count. The cause of EMS was discovered to be a bad batch rather than the supplement itself.

It is also worth noting that the Food and Drug Administration (FDA) currently does not regulate supplements.

There are, however, a number of independent testing agencies that examine supplements for purity and potency. People should look for supplements that have been certified by third-party evaluators to reduce their exposure to bad products or ineffectiveness.

Additional resources

Many foods naturally contain L-tryptophan. Some food sources are:

  • turkey
  • tuna
  • nuts
  • seeds

The amount of the nutrient present in food is unlikely to have any positive or negative effects on a person’s sleep or mood.

L-tryptophan substitutes

Melatonin is another supplement that can help with insomnia or sleep disorders. Melatonin is a hormone produced by the body to promote sleep in the evening and wakefulness in the morning.

Non-supplement-related sleep aids can also be tried. Some suggestions for getting a better night’s sleep include:

consuming warm milk

ensuring that the bedroom is cool and dark exercising during the day

When should you see a doctor?

Before beginning any supplement, people should consult with their doctor. People who take antidepressants, in particular, should consult their doctor before taking L-tryptophan supplements.

If people experience any unusual symptoms after taking the supplement, they should discontinue use and consult their doctor.

In conclusion, L-tryptophan may be an effective sleep aid as well as a treatment for other conditions such as chronic pain, anxiety, depression, or PMS.

However, the supplement may not be suitable for everyone and may not be beneficial in all cases. Before beginning a new supplement, people should consult with their doctor, and they should discontinue use if they experience any side effects.

More research is needed to determine whether L-tryptophan is safe and effective in the treatment of any of these conditions.