Sex and Cancer: Sexually transmitted infections
Remember: Cancer cannot be passed from one person to another, including through sex.
The treatment that you get for your cancer can lower your immune system, which puts you at higher risk of some genital infections and getting symptoms from viruses like HPV or genital herpes.
It is really important that you let your cancer team know if you think you need an STI test,or have symptoms which may be due to an STI. You will need to receive treatment for the STI in a safe way alongside your cancer treatment. Please do not have treatment for an STI without first telling someone on your team, so that they can ensure that the treatment is safe to have at the same time as your cancer treatment.
This page gives a very brief overview of the most common types of STI but there are booklets available on each infection that contain more detailed information available from your hospital, GP surgery, or local sexual health clinic.
What does having a full sexual health screen involve?
If you are sexually active, it is recommended that you have a sexual health screen as soon as possible so that any infections that may be present can be treated quickly. This is to reduce the risk of complications developing as they are more likely if you are having treatment for cancer.
Many sexual health clinics can provide online STI testing kits that you can order from their website. It is best to check the website of your local sexual health provider to see if they provide this service.
If you do not have any symptoms, testing will usually involve providing a urine sample and if you have a vagina, a vaginal swab too. You can take these samples yourself.
If you have oral and anal sex, the clinic can also offer throat and rectal swabs as required. Sexual health clinics usually offer syphilis and HIV testing as part of a sexual health check up.
If you have symptoms, it is important to speak with your sexual health clinician so that any additional test that may be relevant to your symptoms can be arranged or carried out.
Below are listed some common STIs and some other conditions to be aware of:
Chlamydia
Chlamydia trachomatis is one of the most common bacterial STIs in the UK and the most frequently diagnosed STI in England. It is generally quite easy to treat and cure. However, if it is not treated it can lead to complications.
Chlamydia can infect the urethra (tube you pee from), the uterus (womb), the cervix (entrance to uterus), the ovarian (fallopian) tubes, testicles, rectum (back passage), throat, and eyes. Most people who have chlamydia do not have any obvious signs or symptoms. Symptoms can include:
People registered female at birth
(e.g. cis women, trans men, non-binary people):
- bleeding between periods and/or heavy periods (if you have them);
- bleeding after sex;
- pain and/or bleeding when you have vaginal sex;
- lower abdominal pain (pelvic pain);
- pain when passing urine.
People registered male at birth
(e.g. cis men, trans women, non-binary people)
- a white/cloudy or watery discharge from the tip of the penis (if you have one);
- pain when passing urine;
- pain in the testicles (if you have them).
The only way to be certain if you have chlamydia is to have a test. A test involves either one or a combination of the following:
- a urine sample;
- a swab from inside the vagina (if you have one);
- a swab from the rectum (around the anus);
- a swab from the throat.
Staff can explain how to do the swab so that you can do it yourself in private.
Chlamydia is easily treated with a course of antibiotics that is usually given as a course over 7 days. If chlamydia is left untreated it can cause complications such as pelvic infections, tubo-ovarian abscesses, inflammation of the testicles, and may contribute to infertility.
It is also important that your partner(s) are screened and treated if necessary, so that you do not catch any infections again from them after completing your antibiotics.
Gonorrhoea (The Clap)
Gonorrhoea, also known as “the clap”, is a sexually transmitted infection caused by bacteria. Most of the time, it is treated with an antibiotic injection.
It is found mainly in the semen and vaginal fluids of people who have the infection. It is easily passed on from one person to another through sexual contact. The bacteria can live inside the cells of the cervix (entrance to uterus), the urethra (tube you pee from), the rectum (back passage), the throat, and sometimes the eyes.
As gonorrhoea is developing more resistance to antibiotics, you will usually have an additional swab to check for antibiotic resistance and will be invited back to repeat the test, usually 2-3 weeks later, to make sure the infection has cleared.
If it is left untreated, gonorrhoea may spread to other parts of the body and cause further complications including reduced fertility, or infertility.
It is also important that your partners are screened and treated if necessary, so that you do not catch any infections again from them.
Syphilis
Syphilis is caused by the bacteria known as Treponema Pallidum. It is not as common as some of the other STIs. It can affect any part of the body and most common signs are ulcers on the genitals, mouth, skin rashes, and swollen lymph nodes. Some people can also have no symptoms and it is only detected via a blood test. Syphilis can be passed on through:
- unprotected oral, vaginal, or anal sex with someone who has syphilis;
- touching ulcers or weeping rashes from someone who has syphilis;
- through blood transfusion (very rare in the UK);
- from an infected mother to an unborn child.
If you are diagnosed with syphilis it is likely that you will be asked to see a sexual health specialist for treatment. It is easily treated with injection of antibiotic penicillin, usually to the muscle of your buttocks (bum cheek).
Human papillomavirus (HPV)
The human papillomavirus (HPV) is a common virus that typically infects skin and any moist membrane (mucosa). This includes the genitals, back passage, and mouth and it can be passed between people through intimate skin-to-skin contact involving these areas, such as vaginal, anal, and oral sex, or from sharing sex toys.
HPV does not cause a problem for most people but there are more than 100 types of HPV, which can be divided into two categories: “high risk” and “low risk”. Only some types of HPV infect the genital skin and are classed as sexually transmitted infections (STIs). High risk types of HPV can sometimes lead to certain cancers, although this is rare. This is why it is important to attend cervical screening (if you have a cervix).
You can reduce your risk of HPV by using a condom or another barrier method, and by getting a HPV vaccination.
The HPV vaccine given in the UK (Gardasil) protects against HPV types 6, 11, 16 and 18. HPV types 16 and 18 are responsible for approximately 70% of cervical cancer cases, 75–80% of anal cancer cases, 70% of HPV-related precancerous lesions of the vulva and vagina, 75% of HPV related precancerous lesions of the anus. HPV type 16 is responsible for almost 90% of HPV-positive oropharyngeal (mouth and throat) cancers. HPV types 6 and 11 are responsible for approximately 90% of cases of genital warts.
Children aged 12 to 13 years (who were born after 1 September 2006) are offered the HPV vaccine as part of the NHS vaccination programme.
The vaccine helps protect against cervical cancer, some mouth and throat cancers, and some cancers of the anal and genital areas.
Since April 2018, men who have sex with other men (MSM), trans women, and non-binary people registered male at birth who are up to the age of 45 have been eligible for free HPV vaccination on the NHS when they visit sexual health services and HIV clinics in England.
Trans men and non-binary adults registered female at birth are eligible if they have sex with men and are aged 45 or under. If they have previously completed a course of HPV vaccination as part of the children’s HPV vaccine programme, no further doses are required.
Genital Warts
Genital warts are the most common viral STI. They are caused by the human papilloma virus (HPV) which can be passed on through sexual and genital skin contact. Most genital warts are caused by HPV 6 and 11.
Not everyone who has the HPV virus develops genital warts and most people will eventually clear the virus from the body over time. However, if your immune system is low you are more likely to develop warts if you carry the infection.
Warts can be found on the vulva, vagina, cervix (entrance to uterus), penis, scrotum, urethra (tube you pee from), and on or inside the anus.
If you develop any new genital bumps, it is best to get this examined by your doctor or nurses to confirm the diagnosis.The warts can be treated in a number of different ways such as freezing the warts or home based treatments that might use medical creams. It is best to discuss with the staff at the sexual health clinic what treatment is best for you.
Genital Herpes
Herpes infection is a common viral infection in the UK. Most people (about 70%) will have been infected with either type 1 or type 2 of the virus by their 25th birthday. It is a viral infection that can spread via skin to skin contact and can happen during any kind of sex.
Most people with herpes infection don’t realise they have it. The most common symptom is the presence of painful ulcers and some people can feel very unwell with this. The doctors or nurses in the sexual health clinic can swab any ulcers to test for the herpes virus. Treatment with antiviral Aciclovir can be used to shorten the duration of the episode and improve symptoms. You may also be prescribed local anaesthetic gel to help with symptoms.
Most of the time, if the person experiences very mild symptoms, no treatment is necessary. If you have any concerns, or are experiencing recurrent or severe symptoms, we recommend you discuss this with your sexual health clinic and your cancer specialist nurse for expert advice. Some people can take regular Aciclovir to suppress recurrent attacks of herpes infection.
HIV
HIV stands for Human Immunodeficiency Virus. Once someone is infected with HIV the virus will remain in the body for the rest of their life. If left untreated, the virus weakens and damages the immune system so that it cannot fight off infections.
HIV can be passed from one person to another through sexual contact, and in a number of other ways including sharing syringes (needles). The body fluids that can carry and transmit HIV are, vaginal fluid, semen, anal mucous, breast milk and blood.
Many people with HIV have no signs or symptoms and the only way of finding out is by having a blood test.
HIV can increase the risk for certain cancers because it can lower your immune system’s ability to respond to disease. If you are HIV negative, you should continue to practise safer sex such as using condoms or dental dams. You may also want to consider taking pre-exposure prophylaxis (PrEP), which is free from NHS sexual health clinics and further reduces the risk of acquiring HIV.People living with HIV on effective treatment can’t pass it on to their partner(s). This is what is meant by the phrase ‘Undetectable equals Untransmittable’ (U=U). You can find more information about this on the Terrence Higgins Trust website.
Trichomoniasis
Trichomoniasis is caused by a parasite called Trichomonas vaginalis (TV).
Symptoms of trichomoniasis usually develop within a month of infection but up to half of all people will not develop any symptoms (though they can still pass the infection on to others).
The symptoms of trichomoniasis are similar to those of many other STIs, so it can sometimes be difficult to diagnose. Symptoms can include:
People registered female at birth
(e.g. cis women, trans men, and some non-binary people):
- abnormal vaginal discharge that may be thick, thin or frothy and yellow-green in colour;
- producing more discharge than normal, which may also have an unpleasant fishy smell;
- soreness, swelling and itching around the vagina – sometimes the inner thighs also become itchy;
- pain or discomfort when passing urine or having sex.
People registered male at birth
(e.g. cis men, trans women, and some non-binary people)
- pain when peeing or during ejaculation;
- needing to pee more frequently than usual;
- thin, white discharge from the penis;
- soreness, swelling and redness around the head of the penis or foreskin.
Trichomoniasis can be effectively treated with antibiotics so it is important to let your cancer care team, GP, or local sexual health service know as soon as possible if you have any symptoms.
Non-STI Conditions
Some conditions are not classified as sexually transmitted infections, but you should still be aware of them and see your GP or a sexual health clinic if you have any symptoms.
Shigella
Shigella is a type of bacteria that causes severe stomach upset. It’s passed on through infected faeces (poo), either sexually or through contaminated food.
Some people experience no symptoms. Others get diarrhoea and stomach cramps. You might also have a fever, feel sick, or vomit. In more serious cases, diarrhoea can be severe and may contain blood or mucus (this is also known as ‘dysentery’).
Symptoms usually start a day or two after you become infected and last up to a week, but the infection can be treated with a course of antibiotics.
Thrush
Thrush is not an STI, but can sometimes develop after sex.
It is a common infection that is caused by a yeast fungus (most commonly Candida Albicans). This yeast lives harmlessly on your skin and in the mouth, gut, and vagina. It is normally kept under control by your body. There is an increased risk of developing thrush if you are having chemotherapy treatment or antibiotics.
If you have a vagina, the symptoms you might notice are:
- itching, soreness around the vagina, vulva or anus;
- unusual, white discharge from the vagina that may be thick and can look like cottage cheese;
- pain when having sex.
If you have a penis, the symptoms you might notice are:
- irritation, burning or itching under the foreskin or on the top of the penis (glans);
- redness or red patches, under the foreskin or on the tip of the penis (glans);
- a thin or thicker discharge, like cottage cheese under the foreskin;
- difficulty in pulling back the foreskin.
If you think that you have thrush it is important that you speak to your CNS or your doctor before having any treatment. This is because the treatments for thrush can increase the side effects from certain chemotherapy drugs and must not be taken within two days of receiving chemotherapy.
Treatment can be an antifungal cream, pessary (a small soluble block that is inserted into the vagina), or tablets and the symptoms should usually disappear within a few days of taking the treatment.
Bacterial Vaginosis
Bacterial vaginosis (BV) is not a STI but can develop after sex. It is the most common cause of unusual vaginal discharge, which can develop when the normal environment of the vagina changes.
Many people do not get any signs or symptoms but some may notice a change in their usual vaginal discharge. This may increase, become thin and watery, or change to a white/grey colour and develop a strong, unpleasant smell especially after sex. BV is not usually associated with soreness, itching or irritation.
Having a test involves having a vaginal swab taken and sometimes measuring the PH by wiping a sample of vaginal discharge over a piece of specially treated paper.
Treatment is usually simple and involves taking antibiotics, either as a single dose or over a longer period (up to a week).
Mpox (monkeypox)
Mpox is a viral infection. It is related to smallpox but less severe. It is not an STI but can be passed between people through intimate close contact, including during sex.
Transmission can occur through contact with bodily fluids, sores, blisters, or lesions on the skin or internally, for example, through contact in the mouth, throat, genitals, or rectum.
Mpox has a range of symptoms and some people only experience some of them. Some symptoms are similar to many other viruses and colds, and can include:
- fever;
- headache;
- muscle aches;
- backache;
- swollen glands;
- chills;
- exhaustion.
New unexpected or unusual spots, ulcers, and blisters can develop anywhere on the body, including the face and inside the mouth, throat, and other parts of the body for example the hands and genitals.
Mpox can be more severe for those living with compromised immune systems. If you think you might be infected with mpox, tell your cancer care team straight away.
UTIs
Cancer treatment often increases the risk of getting an infection. Urine tract infections (UTIs) are no different and so it is not uncommon for people with cancer to have a UTI.
When you have a UTI, having sex can cause pain and may irritate the urethra (tube that urine comes out from).
For people with a vagina, having penetrative sex can put pressure on the vagina walls and bladder which may intensify the pain of a UTI.
For people with a penis, sex can also intensify the pain and lead to temporary erectile dysfunction.
Sex should be avoided until all the symptoms of a UTI have gone.