L-citrulline is an amino acid that is thought to help support the immune system and heart functioning.

What are its health benefits?

L-citrulline is a non-essential amino acid that is converted by the kidneys into another amino acid called L-arginine, which in turn converts into nitric oxide. These compounds are beneficial to the health of your heart and blood vessels, and may also play a role in supporting the immune system.

It occurs naturally in the body and is also found in watermelons.

An L-citrulline supplement may have the following benefits:

  • Helping to lower blood pressure in individuals showing signs of pre-hypertension (readings of 120/80 to 139/89), an early warning sign of high blood pressure (hypertension).
  • Assisting in the relief of symptoms associated with mild-to-moderate erectile dysfunction.
  • Assisting wound healing in diabetes patients, and may improve muscle protein levels that would assist malnourishment in, for example, the elderly.
  • Assisting in the management of intestinal-related conditions, such as short bowel syndrome, coeliac disease and bowel damage caused by radiation.
  • Assisting in the management of certain genetic disorders and health conditions, for example, liver disease.
  • Assisting in the management of Parkinson’s disease and certain dementias.
  • Assisting muscle building and improving athletic performance, although research indicates that it does not assist already well-trained athletes to perform better.
  • Assisting in the relief of symptoms associated with sickle cell disease.

Do you have a deficiency?

L-arginine (the first by-product of L-citrulline) deficiency may result in hypertension, atherosclerosis, low sperm count, poor wound healing, skin rash, constipation, among others.

Low levels of nitric oxide (the second by-product) may cause fatigue and low energy/stamina, decreased libido, poor concentration, insomnia, depression and high blood pressure (hypertension).

Find it in these food sources

L-citrulline is found in rich supply in watermelon, but can also be obtained from other melon varieties and cucumbers.

Recommended dietary allowance (RDA)

The RDA for L-citrulline depends on the condition it is being used for. Generally up to 9g divided throughout the day can be used, although optimal doses have not been established.

Consult with your Clicks pharmacist about the correct dosage for you.


Safety during pregnancy and breastfeeding has not been established, so it is advised not to take L-citrulline supplements during these periods.

L-citrulline supplements may affect the way other drugs work in your body, so avoid if you’re taking nitrates for heart disease, erectile dysfunction medication, or medication for blood pressure.

Possible side effects

Side effects could include:

  • Drop in blood pressure if taken with certain erectile dysfunction medication

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

This message 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