The hole at the end of the penis is the opening of the urethra (the tube for urine and semen that is inside the penis). Discharge is usually a sign of infection in the urethra.
Non-specific urethritis (NSU) is a common cause of discharge. ‘Urethritis’ means inflammation of the tube, and ‘non-specific’ means that is difficult to know the exact cause. NSU causes a discharge that is usually clear, and is worse in the mornings. You may find it uncomfortable to pass urine, and you may feel irritation along the urethra inside the penis.
NSU is caught during sex. Several types of bacteria may be responsible; about half of cases are caused by Chlamydia and about 40% are caused by other bacteria (such as Ureaplasma and Mycoplasma). These bacteria do not cause a discharge in women, or any other symptoms in the early stages, so most women do not know that they have an infection.
In women, Chlamydia can travel upwards into the Fallopian tubes (the tubes that carry the eggs from the ovaries to the womb), and can eventually affect the tubes, making the woman infertile. For this reason you need treatment, so that you do not pass the infection on to a female partner.
Gonorrhoea is caused by a bacteria called Gonococcus – you will find more information in the section on gonorrhoea. Like NSU, it is caught during sex, and often causes a discharge and pain when you pass urine. The discharge can be any colour – yellow, green, white, cloudy or clear. The symptoms may be so slight that you hardly notice them, or there may be a lot of discharge. Gonorrhoea can spread to the testicles, causing pain, swelling and redness. As with NSU, the woman you caught it from was probably unaware that she was infected; only 10–20% of women with gonorrhoea have a discharge.
Inflammation. Occasionally, the urethra can become inflamed without there being any infection. For example, if you poke anything up the urethra you can damage the lining, which will become inflamed and cause a discharge. Similarly, antiseptics, strong soaps or perfumed bubble baths can inflame the urethra if you are very sensitive to them. And check to make sure the discharge is actually coming from the urethral opening, rather than from a sore area under the foreskin.
What you should do
Any discharge from the penis needs to be checked out by a doctor – either your family doctor or, preferably, a doctor at a genitourinary medicine clinic. This is because chlamydia and gonorrhoea can be easily treated with the correct antibiotics, but can cause problems to you and your future partners if they are not treated properly. Some types of the bacteria that cause gonorrhoea are resistant to certain antibiotics, but the genitourinary medicine clinic will be able to test you to select the correct one.