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It is estimated that nearly half a million people in the UK are diagnosed with a sexually transmitted infection (STI) every year, and since some are passed on unwittingly because they are either symptomless in the early stages or display symptoms that can easily be confused with other health issues, that figure could be significantly higher.
If you think you might be at risk of catching an STI, here are the symptoms you should watch for.
One of the most common STIs in the UK, chlamydia is easily transmitted during sex, and since there are often no symptoms to begin with, many are unaware they have been infected. Left untreated, however, it can lead to serious long-term health problems, including infertility.
Both men and women may experience pain or a burning sensation when urinating. Other symptoms for men include a white, cloudy or watery discharge from the tip of the penis, and pain in the testicles, while for women, unusual vaginal discharge, pain in the lower abdomen during or after sex, and bleeding after sex or between periods.
It is diagnosed with a simple urine test or swab, and is treated with antibiotics.
This bacterial infection is another tricky customer, as the NHS reports that around 50 per cent of women and 10 per cent of men do not experience any symptoms.
Symptoms to watch for though are largely similar to Chlamydia, though yellow or green discharge, either from the penis or the vagina, is a sign of gonorrhoea. Once again, it can cause long-term health problems if left untreated, but antibiotics will get rid of the infection.
Commonly known as 'crabs', pubic lice can be passed on through close genital contact. Though they are usually to be found, as you might expect, lurking in the pubic hair, they can also live in body hair elsewhere, including beards and occasionally eyebrows or eyelashes.
Many people do not notice any symptoms for several weeks, but itching in the affected area is usually the first sign. You may also spot the lice or eggs on the hairs. Treatment is by way of creams or shampoos that are available over the counter or via a prescription.
Caused by the human papilloma virus (HPV), genital warts can be passed on by skin-to-skin contact. If you spot small fleshy growths, bumps or changes in the skin surrounding your genital or anal area, it's likely you have contracted the virus. Though commonly painless, genital warts may cause itching, redness and occasionally bleeding. Creams and cryotherapy (freezing) are typically used to treat the problem, though other treatments are available.
Caused by the same virus that causes cold sores, the herpes simplex virus or HSV, people who have contracted genital herpes often display symptoms within a few days. Small, painful blisters or sores may appear in the genital area, and they can be itchy, tingly or make urinating painful.
Unfortunately, once you've contracted the virus, you're stuck with it as there is no cure. It will, however, remain dormant for the majority of the time, though most people experience flare-ups. The symptoms can usually be controlled with the help of antiviral medication.
There are many more STIs in circulation, including syphilis and HIV, and practising safe sex really is the best advice. If you believe you are at risk, however, do attend a sexual health clinic or visit your GP and get checked out.