Hi dear, Thanks for choosing HCM. Penile discharge happens when there is any kind of inflammation in Urethra, people get tested for STD, to see if the cause of the inflammation is due to Sexually transmitted infections. If you tested negative for STD, then we can say that the reason for you condition is not due to STD. However, there are also other causes of penile discharge, you haven t included in your question if you have any other symptoms other than discharge. So if you have swollen and itchy glans with or without pain during urination and STD shows negative then it could be due to Fungal infection. Patients with fungal infection are given Clotrimazole Cream to apply on area 3 times a day for at least 10 days. If you don t have other symptoms except penile discharge, it could be due to inflammation in your urethra caused by trauma or due to prostate discharge. For your case I think it’s most likely to be discharge from prostate, because rectum is near the prostate and when some men are constipated and pass stool it might cause some compression on the prostate which will cause discharge from penis. Since you mentioned that the discharge is white (prostate discharge is white semen like) and that it happens during dehydration (maybe you get constipation due to dehydration), then it could be actually just that. My advice for you is the following. 1.If you think that this happens with constipation and discharge mostly occurs after going to to the toilet for passing stool then it s perfectly normal thing and you don t need any treatment. just drink more water. 2.If you have discharge with the other symptoms i mentioned above, then go to Urologist and ask him to do swab test on the discharge and discuss with him about possibility of fungal infection. Hope this helped If you have more questions don t hesitate to ask Kind regards