L-citrulline
L-citrulline
Supplements. Modern nutrition.
Also called Citrulline, Citrulline malate, Citrulline DL-malate
Pinyin: guā ān suān
Spanish: L-citrulina
Can lower blood pressureAn amino acid found in watermelon that the body turns into arginine, and it is sold mainly for blood pressure and exercise.
Did you know? Citrulline was first isolated from watermelon in the early 1900s, and its name comes from Citrullus, the botanical name for the watermelon genus.
What it may help, and how strong the proof is
- Blood pressure. Reviews of small trials find a modest drop in the top blood pressure number, about 4 points on average. Results vary, and the trials were small.See the research: 51 studies in peoplePromising proof
- Muscles & exercise. Small trials report less muscle soreness after hard exercise, and a 2020 review of small trials agreed. Effects on exercise performance are mixed.See the research: 51 studies in peoplePromising proof
Parts of the body
Traditional use
Citrulline itself has no folk history. Watermelon, its best-known food source, has a long place in African cooking and traditional remedies.
How it is classified
- Herbal actions
- Nutritive, Circulatory. Energy: neutral.
How people take it
Blood pressure studies used about 3 to 9 grams a day for 1 to 17 weeks. Food amounts are much smaller, so watermelon does not match these doses. Ask a doctor before using supplements if you take blood pressure medicines.
Powder, capsule, food and juice.
Where to get it
Watermelon is the best-known food source, and cucumbers, cantaloupe and some squash also contain citrulline. Powders, capsules and citrulline malate blends are sold in health stores and online.
Be careful
Citrulline is usually well tolerated, though high doses can cause stomach upset or diarrhea. It can lower blood pressure, which adds to blood pressure medicines and to sildenafil or tadalafil. Pregnancy and breastfeeding are not well studied, so skip high-dose products unless a doctor advises.
Avoid if: low blood pressure; pregnancy (high doses); breastfeeding (high doses).
Mixing with other things
- Works well together
The body turns citrulline into arginine, and citrulline raises blood arginine more than arginine itself does. Some people take both.
- Works well together
Watermelon is the best-known food source of citrulline, and the whole fruit adds water and fiber.
- Use cautionBlood pressure medicine (lisinopril, amlodipine, losartan)
Citrulline can lower blood pressure, which adds to blood pressure medicines.
Adds up with others that may lower blood pressure: , , , , , , , , , , , , , and 16 more.
The honest take
Citrulline is a normal part of watermelon and is well tolerated by most people. Several small trials suggest a modest drop in blood pressure, but the results vary. Exercise claims are mixed, so the evidence is not strong yet.
Sources
Each “See the research” link opens PubMed, the U.S. National Library of Medicine's index of medical studies, showing only trials and reviews done in people. The number tells you how much a use has been tested, not whether it worked. The proof rating tells you that.
Study counts checked October 2026.