Serotonin sends signals between your nerve cells. It may help regulate many body functions, including mood, bowel movements, and sleep, among others.

Serotonin is a chemical that nerve cells produce, and it sends signals between your nerve cells. Serotonin is found in many parts of your body: in your digestive system, blood platelets, and throughout the central nervous system.

It’s also thought to play a role in regulating your mood.

Serotonin is made from the essential amino acid tryptophan. This amino acid must enter your body through your diet and is commonly found in foods such as meat, dairy products, eggs, and nuts.

High levels of serotonin in your blood may be a sign of carcinoid syndrome. This involves a group of symptoms related to tumors of the:

  • small intestine
  • appendix
  • colon
  • bronchial tubes

A doctor can request a blood test to measure the amount of serotonin in your blood to help diagnose the condition or rule it out.

Serotonin impacts every part of you, from your emotions to your body and motor skills. It helps with sleeping, healing, and digesting. Serotonin is also thought to be a natural mood stabilizer.

Serotonin helps your body to :

  • regulate anxiety
  • experience happiness
  • heal wounds
  • stimulate nausea

Here’s how serotonin acts in various functions across your body:

  • Bowel movements: About 90% of the serotonin in your body is produced in your intestines. It helps control your bowel movements and function.
  • Mood: Serotonin in the brain is believed to regulate feelings including happiness and anxiety. Selective serotonin reuptake inhibitor (SSRI) medications are thought to relieve mood disorders by increasing serotonin activity in your brain.
  • Nausea: Serotonin in your stomach and intestines helps your body initiate nausea and vomiting in response to illness, foods, or other conditions.
  • Sleep and waking: Your ability to stay awake is controlled by neurotransmitters including serotonin. While you sleep, the chemical is involved in switching between REM and non-REM sleep.
  • Blood clotting: Platelets in your blood store serotonin. When your body needs to repair damage, platelets release serotonin to help stop bleeding and heal wounds.
  • Sex: Serotonin is involved in controlling the body’s sexual functions. This may be why medications that affect serotonin levels are associated with sexual side effects.

Serotonin and mental health

Many common medications for mental health conditions are thought to work by changing how your brain uses serotonin.

Among researchers, there’s some debate about the role serotonin plays in mental health. Early theories suggested that low serotonin causes depression. However, the truth is likely more complicated.

Mood disorders may result from a combination of factors including changes in the brain, life experiences, and health conditions, according to the National Alliance on Mental Illness.

Even so, antidepressant medications continue to be an important first-line treatment for mood disorders, along with psychotherapy. Always follow your doctor’s instructions when taking antidepressant medications.

Serotonin vs. dopamine

Like serotonin, dopamine is a chemical communicator that’s found in your brain and many other parts of your body.

Both of these neurotransmitters are associated with your mental well-being, so it can be easy to confuse them. But there are also some key differences between the two.

Here are several ways that serotonin and dopamine may act differently in your body:

Where it’s producedmainly in your gutmainly in your brain
Moodstabilizes mood and anxietyaffects motivation and pleasure
Depressiontargeted in common depression treatmentsfew depression treatments target it
Sleephelps regulate sleep and wakefulnesshelps you feel more alert

You may be able to increase your serotonin levels through medication and more natural options.


SSRIs are the most commonly prescribed type of antidepressant medication. They increase serotonin levels in the brain by blocking reabsorption of the chemical, so more of it remains active. SSRIs include fluoxetine (Prozac) and sertraline (Zoloft), among others.

When you’re taking medications that affect serotonin, you shouldn’t use other medications or supplements without first talking with your doctor. Mixing medications may put you at risk of a serious condition called serotonin syndrome.


Some supplements may have the ability to raise serotonin levels. However, they’re not a replacement for medications prescribed by your doctor and should not be taken alongside other medications.

Supplements that may affect serotonin include:

  • St. John’s wort: The herb St. John’s wort increases serotonin in the body. Some believe it is effective for treating depression, but this has not always been supported by research.
  • SAMe: This supplement is promoted as a treatment for depression, but more studies are needed to understand its effects on mood and serotonin levels.
  • Tryptophan: This substance can be converted into serotonin in your brain, potentially raising your serotonin levels. Some research suggests it could help improve mood and reduce anxiety.

It’s also important to know that these supplements can increase your risk for serotonin syndrome, and can cause other side effects and interactions. Always talk with a doctor before trying any supplements or herbal remedies.

Natural serotonin boosters

The following strategies may help you boost your serotonin levels and improve your mood:

  • Exposure to bright light: Bright sunlight may help your mood, which is why light therapy is commonly recommended for treating seasonal depression. SAD lamps are an option for home therapy in winter or when access to bright sunlight is difficult.
  • Exercise: Regular exercise has many benefits for your general health. It can have mood-boosting effects, and it may trigger the release of serotonin.
  • Health-promoting diet: Following a balanced diet lowers the risk of many health conditions. Although research is limited, eating foods that may promote serotonin production could positively affect mood.
  • Meditation: Meditating can help relieve stress and promote a positive outlook on life. Some research suggests that it may raise serotonin levels, though more evidence is needed.

Medications, supplements, and other substances that increase serotonin levels in your body can lead to serotonin syndrome.

Serotonin syndrome can happen when you:

  • start taking a new medication
  • increase the dosage of an existing medication
  • take more medication than the amount prescribed
  • use an additional medication, supplement, or illegal drug that also affects serotonin levels

Medications, supplements, and substances that affect serotonin levels include:

  • SSRIs
  • monoamine oxidase inhibitors (MAOIs)
  • dextromethorphan
  • many medications prescribed for mental health conditions
  • St. John’s wort
  • SAMe
  • tryptophan
  • amphetamines
  • cocaine
  • MDMA (ecstasy)
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The symptoms of serotonin syndrome include:

  • tremors
  • sweating
  • nausea
  • vomiting
  • restlessness

Severe symptoms can include:

There is no single test that can diagnose serotonin syndrome. To diagnose the condition, your doctor will conduct a physical exam and may request other tests such as:

In mild cases, your doctor may ask you to stop taking the serotonin medication so that your symptoms can resolve. In more serious cases, your doctor may also use additional medications to treat the symptoms. Hospital treatment is typically necessary to manage severe serotonin syndrome. Usually, symptoms resolve within 24 to 72 hours.

If you suspect serotonin syndrome, it’s important to get medical attention immediately. Serotonin syndrome can be life threatening if left untreated.

Serotonin affects every part of your body. It’s responsible for many of the important functions that get us through the day.

Sometimes, a serotonin imbalance can mean something more serious. It’s important to pay attention to your body and talk with your doctor about any concerns.