Theanine is an amino acid (a building block for protein) that occurs naturally in tea, particularly green tea, and may aid tea’s calming and rejuvenating properties.

What are its health benefits?

Theanine has a structure that is similar to glutamine, an amino acid that occurs naturally in the body, which is believed to help with normal brain function, digestion and the health of your muscle cells, aiding immune function. It is also found in mushrooms.

It’s available as a supplement and is used in energy and ‘relaxation’ drinks too.

Reportedly, theanine may have the following health benefits:

  • Assists in the management of anxiety and thus makes people feel more relaxed
  • Assists in the management of blood pressure
  • Assists in the production of the body’s feel-good hormones, serotonin and dopamine, improving mood that is helpful for depression
  • Aids memory and learning
  • Supports the immune system
  • It is often used in bodybuilding to improve focused training

Recommended dietary allowance (RDA)

There is currently no consensus regarding the correct amount of theanine you should take, but a dosage of between 85 to 250mg three times per day is believed to be sufficient.

Consult with your Clicks pharmacist regarding recommended dosages.


Little is known about the effects of taking theanine during pregnancy, so women who are pregnant or breastfeeding should rather steer clear of theanine.

Possible side effects

Theanine is generally safe to consume orally for short periods of time, however, its interaction with other substances may produce negative side effects, including:

  • Because theanine may lower blood pressure, it may cause blood pressure to drop too much if taken together with certain medications for high blood pressure (hypertension).
  • Theanine may reduce the effectiveness of stimulants, because it may counteract the stimulants’ effects of increased heart rate by slowing down the nervous system.

Ensure you discuss dietary supplementation with your Clicks pharmacist to avoid the potential for side effects and adverse interactions with medications.

This medicine has not been evaluated by the Medicines Control Council. This medicine is not intended to diagnose, treat, cure or prevent any disease.

The accuracy of this information was checked and approved by Clicks' pharmacist Waheed Abdurahman in September 2015