Overview

L-citrulline is an amino acid found in watermelon. It is also made in the body. The body changes L-citrulline into another amino acid called L-arginine.

The name citrulline comes from Citrullus vulgaris, the Latin term for watermelon. Unlike some amino acids, L-citrulline isn't used to make protein, but it might help increase other chemicals the body needs to make protein. It might also help improve blood flow and reduce blood pressure.

People use L-citrulline for athletic performance, sickle cell disease, erectile dysfunction (ED), high blood pressure in the lungs, heart disease, and many other conditions, but there is no good scientific evidence to support most of these uses.

Uses & Effectiveness

Possibly Effective for

  • Athletic performance. Taking L-citrulline by mouth might help improve some types of exercise performance such as weight lifting. But its effects on aerobic exercises such as running are unclear.

Possibly Ineffective for

  • Age-related muscle loss (sarcopenia). Taking L-citrulline by mouth does not seem to increase muscle strength in older adults who regularly exercise.

There is interest in using L-citrulline for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: L-citrulline is possibly safe when used for up to 2 months. It's usually well-tolerated. Some people might experience stomach discomfort or heartburn.

Special Precautions and Warnings

When taken by mouth: L-citrulline is possibly safe when used for up to 2 months. It's usually well-tolerated. Some people might experience stomach discomfort or heartburn.

Pregnancy and breast-feeding: There isn't enough reliable information to know if L-citrulline is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: L-citrulline is possibly safe when taken by mouth.

Surgery: L-citrulline might affect blood pressure. It might interfere with blood pressure control during and after surgery. Stop taking L-citrulline at least 2 weeks before a scheduled surgery.

Interactions

    Moderate Interaction

    Be cautious with this combination

  • Medications for high blood pressure (Antihypertensive drugs) interacts with L-Citrulline

    L-citrulline might lower blood pressure. Taking L-citrulline along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely.

  • Medications for male sexual dysfunction (Phosphodiesterase-5 inhibitors) interacts with L-Citrulline

    L-citrulline might lower blood pressure. Some medications for male sexual dysfunction can also lower blood pressure. Taking L-citrulline along with these medications might cause blood pressure to go too low.

Dosing

L-citrulline has most often been used by adults in doses of 1.5-5 grams by mouth daily for up to 4 months. Speak with a healthcare provider to find out what dose might be best for a specific condition.
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