A sexually transmitted infection is an infection which spreads from person to person through sexual contact such as anal, vaginal, or oral sex, and skin to skin contact. Sexually transmitted infections can be caused by viruses, bacteria, and parasites and, if left untreated, can progress to a serious disease.

Not all sexually transmitted infections have symptoms so you may not know if you have one. If you are having sex with a number of different partners, or if you are experiencing discomfort in your genital area, it is a good idea to get an STI test.

Having another sexually transmitted infection, can make it easier to get HIV. For example, an STI could cause a sore or break in the skin and make it easier for HIV to enter your body. If you have a weakened immune system because of HIV, then it can be easier to get an STI.


Syphilis is an extremely infectious STI caused by a bacteria.

It can be passed on through sexual and skin-to-skin contact with a syphilis sore.

The infection can also be passed on to an unborn baby during pregnancy and, if left untreated, may lead to infant death.

Over half of syphilis cases have no obvious symptoms, but for those that do, symptoms include:

  • Sores on the body, penis, vagina, or anus.
  • A rash or spots that are not itchy, often on the palms or soles of the feet.
  • Common cold symptoms.

Condoms can help to protect you, but you can still catch syphilis through skin-to-skin contact from other parts of the body.

Syphilis is usually treated with antibiotics.

If you think you might have syphilis the best thing to do is get tested.

The only way to know for sure is to get tested.


Gonorrhoea is a sexually transmitted bacterial infection caused by unprotected vaginal, oral, or anal sex. Condoms are a good way to prevent transmission. As with other STIs gonorrhoea does not always have visible symptoms – but when it does, they may include:

  • Soreness or redness at the opening of the penis
  • Unusual anal, vaginal, or penile discharge
  • Pain or discomfort while urinating

Antibiotics are usually a good treatment, but if left untreated it can increase a person’s chance of getting or transmitting HIV.

If you think you might have gonorrhoea the best thing to do is get tested.

The only way to know for sure is to get tested.

Genital warts

Genital warts are a sexually transmitted infection caused by certain types of the Human Papillomavirus (HPV). It can be passed on through skin-to-skin contact, vaginal, oral, and anal sex.

Genital warts affect the moist tissues of the genital areas or mouth, and can look like small, skin-coloured bumps or cauliflower shapes if close together. Condoms can help reduce the risk of infection.

Most people with HPV never develop symptoms and the virus will clear up after a couple of years. However, there are more than 150 types of HPV, and at least 14 of these are high-risk types that could lead to cancer.

There is free immunisation for HPV available in New Zealand for anyone aged 9 to 26, and for non-residents under the age of 18. Children are offered vaccination for HPV in year eight of school.

If you think you might have genital warts the best thing to do is get tested.

The only way to know for sure is to get tested, and it is a great idea to get vaccinated.

Genital herpes

Genital herpes is a common STI caused by the Herpes Simplex virus or HSV. It is passed on through unprotected anal and vaginal sex so using condoms is your best protection.

Many people don’t show symptoms, but they include sores or small blisters in the genital area (around the vagina in women or on the penis in men), or cold sores on the face which can be very painful. You can only be tested when you show any symptoms.

There is no cure for genital herpes – it stays with you for life, but symptoms can be treated, usually with anti-viral pills.

If you think you might have genital herpes the best thing to do is get tested.

The only way to know for sure is to get tested.


Chlamydia is a common sexually transmitted infection caused by a bacteria and spread through oral, vaginal, anal, or manual sex.

It mostly affects young women but can occur in men of all ages.

Most people who are infected have no symptoms, but when symptoms do appear they include pain when urinating (going for a pee), vaginal discharge, and discharge from the penis. Chlamydia can also affect the eyes and throat. Using condoms can help prevent infection and transmission.

The infection can also be passed from mother to baby during childbirth.

Chlamydia can be cured by antibiotics.

If you think you might have chlamydia the best thing to do is get tested.

The only way to know for sure is to get tested.


Thrush is a fungal infection caused by the yeast ‘Candida Albicans’, which happens naturally in many parts of the body, including the mouth, vagina, penis and anus.

A thrush infection occurs when the natural yeast present in these parts of the body overgrows. Excess yeast growth can be caused by a number of things, including lots of sex, excessive sweating, a reaction to antibiotics and use of soap and detergent.

Thrush is not considered a sexually transmitted infection (STI), but it can sometimes be passed on through sex.

Symptoms of thrush include:

  • Whitish, velvety lesions in the mouth or tongue
  • In women, abnormal vaginal discharge, genital itching or burning sensation when urinating
  • Men may have an itchy and red penis or wider groin area.

Thrush can be treated with anti-fungal creams, oral tablets of vaginal pessaries. Medication for thrush can be bought at your local pharmacy without a prescription. You can also get a prescription for medication by visiting a sexual health clinic or GP/family doctor.