Hello - thanks for asking your question.
While there are many advertisments for herbal supplements, none of them have been studied in consensus medical trials to recommend. There may be anecdotal reports or data from small studies, but to my knowledge, there is no "magic pill" that has been accepted by the general medical community to increase penis size.
There are several surgical procedures. Penis enlargement surgery (phalloplasty) can be done via lengthening or widening using grafts. Other procedures includes liposuction, albugineal/cavernosal (A/C) penile widening and pericavernosal (P/C) penile widening.
Here is a link to some frequently asked questions regarding penile enlargement surgery:
http://www.drwhitehead.com/faqp.html
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.