Depends. Some methods seem to be getting better responses than others. “Studies are being done to improve male girth through injections of hyaluronic acid, which is used as a filler (and is used in orthopedics to improve knee arthritis),” says Dr. Steve from SiriusXM's Weird Medicine on FactionTalk. (Here's a study that supports what Dr Steve is talking about). “The average vagina is 4 inches deep, so girth is much more likely to enhance pleasure for the woman than an increase of length, given that the average male penis length is approximately 5.5 inches,” says Dr. Steve.
Penis enlargement is defined as all means and methods used to temporarily or permanently increase the size of the erect penis and its erectile tissue. Often the word is used in conjunction with a surgical penis enlargement, but it is not limited to surgical means and also includes manual training like jelqing, certain foods and supplements, devices and pumps to stretch the penis.
Eat watermelon. It's not an herb, but it has properties that might help increase the size and duration of erections in a similar way arginine. Watermelon contains an amino acid called citrulline, which gets converted into arginine and leads to the dilation of blood vessels. The fact that watermelon contains citrulline is a relatively new finding, so no studies have been conducted to find out how well it really works or how much watermelon you'd have to eat to see the benefits. However, since watermelon is considered a superfood when it comes to men's health, you can't go wrong by eating plenty of it while it's in season.
The side effects of lengthening surgeries are numerous and include infections, nerve damage, reduced sensitivity, and difficulty getting an erection. Perhaps most disturbing, scarring can leave you with a penis that's shorter than what you started with. Widening the penis is even more controversial. Side effects can be unsightly -- a lumpy, bumpy, uneven penis.