Side Effects of Serotonin Supplements

Serotonin, a neurotransmitter that is involved in the regulation of hunger, sleep patterns and mood, is produced in the brain from the amino acid tryptophan. Serotonin itself is unable to pass through the blood brain barrier, thus the ingestion of serotonin supplements would not be effective in addressing serotonin levels in the brain. A number of other supplements do, however have serotonergic properties. Each of these supplements varies in its effectiveness and in its side effects. Consult your doctor if you are considering taking serotonergic supplements.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


5-hydroxytryptophan, or 5HTP, is a byproduct of tryptophan, the amino acid that the brain uses to create serotonin. It is not readily available from most food sources, but supplements derived from the African plant Grifonia simplicifolia have been developed that offer significant amounts of 5-HTP. MedlinePlus states that 5-HTP is used to treat depression, anxiety, sleep disorders and numerous other conditions 5. The Natural Medicines Comprehensive Database lists 5-HTP as being possibly effective in the treatment of both depression and fibromyalgia. MedlinePlus warns that 5-HTP may cause potential side effects such as heartburn, stomach pain, nausea and sexual problems 5. A more serious side effect, eosinophilia myalgia syndrome, may be due to contamination of some 5-HTP products.


The University of Maryland Medical Center reports that SAMe has shown effectiveness in the treatment of depression, an effect that may be related to SAMe’s role in serotonin production 16. Side effects of SAMe may include dry mouth, headache, a feeling of elation, and gastrointestinal disturbances. SAMe may interfere with sleep patterns and should not be used at night.

St. John’s Wort

St. John’s wort, or Hypericum perforatum, is a serotonergic herb that has long been touted by alternative healthy practitioners as a treatment for depression. The National Center for Complementary and Alternative Medicine states that St. John’s wort has demonstrated superior effectiveness in treating depression when compared to a placebo, and similar effectiveness when compared to prescription antidepressants 4. The possible side effects of St. John’s wort, according to, include:

  • constipation
  • dizziness
  • abdominal bloat
  • photosensitivity 3

Allergic Reactions

Allergic reactions are possible with any supplement or medication, depending on your individual sensitivities. Severe allergic reactions can have fatal consequences. If you experience rash, difficulty breathing, tightness in the chest, tremors, swelling of the face or mouth, or any other sign of severe allergic reaction you should immediately go to a hospital emergency room.