By Dr Sarah Merrifield
Genital thrush is a very common condition, and it has been estimated that 75% of women will experience at least one episode of thrush in their lifetime.1 The condition is also known as vulvovaginal candidiasis, which describes the underlying cause of the disease: a superficial fungal infection of the vagina and/or vulva.
The usual culprit of such an infection is a fungus known as Candida. Candida is in the yeast subgroup of the fungus family, which is why thrush is sometimes referred to as a yeast infection. It normally lives in many parts of the body, but overgrowth can lead to inflammation in the tissues affected. Around 15-20% of women have a type of Candida present in the vagina all the time and don’t experience any symptoms at all.2
The most common symptoms of genital thrush are vulval itching, soreness, pain when attempting sexual intercourse, and stinging when passing urine. These symptoms can also be accompanied by a white, odourless discharge, which has been described by some women as being like “cottage cheese”, or “curdy”, on account of its appearance.
Some women may have all of these symptoms, whereas others may only experience one or two. Thrush is more common if you are pregnant, diabetic, receiving chemotherapy, or taking antibiotics.
How does it cause stinging?
Thrush symptoms occur as a result of the inflammation in the vulva and vagina secondary to the infection. When there is inflammation in any tissue, the body releases substances known as inflammatory mediators, which include the hormones bradykinin and histamine. These hormones can lead to increased blood flow to the tissue, causing redness and swelling.
The hormones irritate the nerves and result in pain signals being sent to the brain.3 Because the inflammation is affecting the tissues in the vulva and vagina, a stinging sensation when passing urine is likely to be felt on the external parts of the genitals. The stinging is triggered by urine passing over the inflamed tissues.
Can other conditions cause stinging when you pee?
There are many other conditions which can cause stinging when you pee, and knowing the symptoms of these may help you work out if your stinging is caused by thrush or something else.
Urine is stored in the bladder before passing down the urethra to exit the body via a hole called the urethral meatus. If there is an obstruction, inflammation or compression within this path or surrounding these structures, then you may experience a stinging or painful sensation when passing urine.
Urinary tract infections (UTIs)
These are very common and are very likely to cause stinging when you pee. The urinary tract consists of the kidneys, bladder and urethra. Infections generally start in the lower part of the tract but can spread further up.
As a UTI affects the urinary tract itself, rather than just the tissues on the outside, the stinging may be felt deeper inside as opposed to stinging felt with thrush, and the urine itself is more likely to display signs of the infection, for example with an unpleasant smell or visible blood.
You are more likely to experience lower abdominal pain or feel generally unwell with a UTI, symptoms which are uncommon with a thrush infection.
Sexually transmitted infections (STIs)
Sexually transmitted infections can cause inflammation in many parts of the body, including the genitalia. There are many different STIs but particular culprits for causing a stinging sensation when peeing are herpes simplex, chlamydia and gonorrhoea.
The herpes simplex virus is very common. Different variations of the virus can cause cold sores on the mouth or painful blisters on the genitals. The herpes virus can lie dormant for a long period of time before causing any symptoms, so it may not immediately follow unprotected sex.
The blisters that appear on the vulva or around it can be extremely tender, hence passing urine can be very painful. The blisters are usually visible, but can sometimes be difficult to see yourself, so it is important to go and get checked out by a doctor who will be able to give you a diagnosis.
Chlamydia and gonorrhoea are particularly common in those aged under 25. Although there are often no symptoms, these infections can present with a stinging sensation when passing urine. Both may also be accompanied by a smelly discharge, in contrast to the discharge seen with thrush, which is generally odourless, or slightly yeasty. With chlamydia and gonorrhoea, there is unlikely to be any itching.
There are several other reasons you may feel stinging when you pass urine, including trauma to the vulva, irritation, or allergy (such as to a soap or washing powder). Any form of blockage or mass in the urethra or bladder can also cause stinging.
The changes to the vulva and vagina associated with the menopause can also cause soreness as well as other skin conditions. In around 10% of cases, there may be one or more infections causing your symptoms.4
If you are experiencing stinging and you are unsure if it is thrush or not, it is best to go and get checked out by the doctor. If thrush is confirmed as the cause, it is treated using anti-fungal medication. For a simple infection, a vaginal pessary can be bought from the pharmacy or prescribed by your doctor. This is often used with a cream to relieve inflammation in the vulva.
If an infection is severe, oral medication may be required. In all cases, it is recommended that you avoid using perfumed soaps, that you avoid wearing tight fitting synthetic underwear, and that you wash with a soap substitute, such as aqueous cream.
If you are unsure what is causing the stinging sensation, contact your local GP surgery. The doctor or practice nurse will examine the area and may need to send a swab or urine sample to confirm the cause. Sexual health or genito-urinary (GUM) clinics are also able to deal with such symptoms and can provide comprehensive testing.