Can watermelon work like Viagra? No. Watermelon contains citrulline, an amino acid the body turns into arginine and then nitric oxide, which relaxes blood vessels — but no study has tested watermelon itself for erectile dysfunction. The one small trial of a citrulline supplement found a modest benefit in mild ED, and its authors call it less effective than the prescription medicines.
Does watermelon help erectile dysfunction?
There is no direct evidence that it does. Watermelon is a good food, and eating it is harmless for most people, but no trial has given men watermelon and measured their erections. What has been tested is L-citrulline as a supplement — at a far higher dose than a few slices of fruit provide.
What did the L-citrulline study find?
In a single-blind study of 24 men with mild erectile dysfunction, 12 of the 24 reported harder erections while taking L-citrulline, against 2 of 24 on placebo (Cormio et al., 2011). The study was small and short, and the authors describe the supplement as less effective than the prescription ED medicines — at best an option for mild ED in men who do not want a tablet.
How is citrulline supposed to work?
The body converts citrulline into arginine, and arginine is used to make nitric oxide, the messenger that relaxes the blood vessels of the penis so it can fill with blood. The same pathway is why L-arginine is sold for erectile dysfunction; it has more trial data than citrulline, and its effect is still small.
Is watermelon a natural alternative to Viagra?
No. Viagra's medicine, sildenafil, works on the PDE5 enzyme and usually starts working in 30 to 60 minutes (healthdirect); no food has an effect like that. The natural steps with the best evidence are not foods at all: losing weight, exercising more and training the pelvic floor. Every option is ranked by the strength of its evidence in natural alternatives to Viagra.
What about other foods and drinks?
The picture is the same: good food, not a treatment. Pomegranate juice was tested in one trial and did not differ significantly from placebo — see pomegranate juice for erectile dysfunction — and the rest are covered in foods and erectile dysfunction.
Is there any risk?
Watermelon itself, eaten as food, is not a risk for most people. The risk is the product sold as a "watermelon" or "natural" Viagra: the TGA has found undeclared sildenafil and tadalafil in sexual enhancement products sold as natural formulas (TGA) — dangerous for men who take nitrates for angina.
The short answer
Eat watermelon because you like it, not for your erections. A citrulline supplement helped some men with mild ED in one small study; if erection problems keep happening, a GP can look for the cause, which is often linked to your general health.
