Sexually transmitted infections/STI’s

Health, Sexuality and HIVRFSLPhoto: Caique Silvero

Read up on chlamydia, gonorrhoea, syphilis, herpes, hepatitis and HPV. We explain how they're transmitted, diagnosed and treated. At the bottom of the page, you'll find information about bacterial vaginosis, urinary tract infections and yeast infections; infections that aren't classified as sexually transmitted infections (STIs) but can be good to know about.

According to the Communicable Diseases Act, you have the right to free testing and treatment for chlamydia, gonorrhoea, syphilis, hepatitis and HIV. If you have any of those sexually transmitted infections you need to tell who you slept with to see who you may have contracted the infection from and to prevent further spread. You therefore need to state who you have had sex with in the last few months, but they will not find out who gave their name.

STI’s increase the risk of transmitting HIV and other STI’s, so get tested regularly!



Chlamydia is the most common sexually transmitted infections in Sweden. A chlamydia infection rarely causes any symptoms and half of those who get chlamydia do not notice it. If you get symptoms, they vary depending on where the infection is. If it is in the penis/vagina, you may experience discharge and/or pain when you urinate. If you have Chlamydia in your anus, you can get discharges from there. Chlamydia in the throat can cause similar symptoms to strep throat and is difficult to pass on, and usually it heals on its own.

Risk of transmission

Chlamydia is easily transmitted through mucous membranes and body fluids. The mucous membrane is found on the glans on the penis, in the vagina, the anus and in the mouth, and that is where you can get chlamydia. Chlamydia is transmitted most easily during vaginal and anal sex, but also during oral sex with a penis. The risk of transmitting chlamydia to the throat during oral sex with a vagina or anus is small, even without protection.

There is a small risk of Chlamydia being transmitted via hands or sex toys between different peoples genitals and the anus. By avoiding transferring bodily fluids from one person to another, for example by washing hands and changing condoms on sex toys, the risk of this is reduced.

The best protection against the transmission of Chlamydia is to use a condom and lubricant or to have sex without penetration.


Testing should be done on the parts of the body where you had sex. Tests for Chlamydia in the penis is usually taken with a urine sample, for people with a vagina, a urine sample is combined with sampling with a cotton swab in the vagina. Samples in the throat and anus are also taken with a swab. The sampling takes a couple of seconds.

It takes about a week from the time you last had sex that involved a risk of transmission before you can get a definite answer to a Chlamydia test.

There are home tests you can order online or buy at a pharmacy. With the home tests, you can only test the genitals. Read and follow the instructions that come with the test. People with a penis submit a urine sample. People with vaginas take a urine sample and use a swab in the vagina. The samples are then mailed to a laboratory for analysis. If you get a positive test result, you must seek medical attention for treatment. If you get a negative answer, you may still have chlamydia in the throat or anus, so if you have had oral or anal sex, you need to go to a testing clinic to be tested.


Chlamydia is treated with a course of antibiotic tablets, usually for nine days.

Good to know

An ongoing Chlamydia infection without symptoms can cause damage to fallopian tubes or testicles, which can make it more difficult to have biological children and can increase the risk of ectopic pregnancy.

LGV ( Lymphogranuloma venereum )

Is a difficult-to-treat type of Chlamydia. It is relatively uncommon but has become more common in recent years, especially among men who have sex with men and live with HIV. It is transmitted in the same way as ordinary Chlamydia but, in addition to the usual symptoms of Chlamydia, can cause sores on the penis, throat or anus and also cause swollen lymph nodes, bleeding and symptoms from the stomach. But it can also be symptom-free and still be passed on. If you have tested positive for Chlamydia and have additional symptoms, you may be diagnosed with LGV. The incubation period for LGV is often long and it can take up to a month before you get swollen lymph nodes. You can get sores earlier. LGV is treated with a double course of antibiotics compared to regular Chlamydia.

Mycoplasma Genitalia

Is a relatively uncommon sexually transmitted disease that is similar to Chlamydia, produces the same symptoms and is transmitted in the same way. If you have symptoms suitable for Chlamydia but test negative for Chlamydia, you can also be tested for Mycoplasma. Mycoplasma is treated with antibiotics, but is not part of the Communicable Diseases Act.



Gonorrhea causes symptoms more often than Chlamydia, but not everyone who has Gonorrhoea gets symptoms. The symptoms usually appear within a week after you’ve had sex. The most common symptoms are discharge from the urethra and a burning sensation when you urinate. Infection in the anus can lead to a burning sensation and bleeding. Gonorrhea in the throat is usually not noticed at all.

Risk of transmission

The infection is transmitted via mucous membranes and body fluids and can settle in the gentials, ass, eyes or throat. Gonorrhea is transmitted most easily during vaginal and anal sex.

Safer sex

The best way to reduce the risk of transmission is to use a condom during anal and vaginal sex, or to have sex other than penetrative sex. Gonorrhea can also be transmitted during oral sex with a penis and to reduce that risk a condom can be used. Both the giver and the receiver are at risk of getting Gonorrhoea.


Tests for Gonorrhoea are taken with swabs in the throat, urethra, cervix, anus and on the inside of the eyelid depending on where the infection may be situated. Gonorrhea in the urethra can also be tested with a urine sample, which is easier than a swab test. The swab testing can be experienced as uncomfortable. If the urine sample shows that Gonorrhoea is present in the urethra, one must follow up with a swab test to ensure what type of Gonorrhoea it is to be able to start the right treatment.

Men who have sex with men often have Gonorrhoea in the throat or anus, which makes testing there extra important.

It takes about a week from the last time you had sex that involved a risk of transmission before you can get a definite answer to a Gonorrhoea test.


Gonorrhea is treated either with a single dose of antibiotics through an injection into a muscle, usually in the thigh or buttock, or with tablets. The treatment may look a little different depending on where on the body the bacteria is and if the bacteria is resistant to certain types of antibiotics. Antibiotic resistant Gonorrhoea is an increasing problem, so a follow-up is always done to see that the treatment has worked.


Syphilis is a serious bacterial infection that had almost disappeared from Sweden for a long time. In recent years, however, the number of cases of Syphilis has increased, especially among men who have sex with men, although the number of people being infected are fairly low.

In 2022, 537 cases of Syphilis were reported in Sweden, the vast majority among men who have sex with men.


Syphilis has different stages. The first stage lasts between three weeks and three months. Then you can sometimes see a crater-like wound that does not hurt and has hard edges where the Syphilis bacteria entered the body. The ulcer may be in a place where it cannot be seen, such as in the anal mucosa. Swollen lymph nodes are common. The wound usually heals on its own within four to eight weeks, regardless of whether you received treatment or not.

After seven to ten weeks, the second stage of the Syphilis infection begins. Then you usually get a fever, swollen lymph nodes and a rash on the body. The symptoms can vary greatly and can “imitate” a variety of diseases. Some get no symptoms at all or so mild symptoms that they don’t notice them. If Syphilis is not detected and treated, after a few years you enter the third stage, which in worst case scenario causes permanent damage to the nervous system and the body’s internal organs.

Risk of transmission

Syphilis is most often transmitted by contact between mucous membranes, but the infection can also be transmitted via skin contact alone on areas with rashes caused by the Syphilis bacteria. Transmission occurs easily during anal and vaginal sex without a condom and during oral sex with penis, vagina or anus. The risk of passing on Syphilis is greatest right at the beginning of an infection. As more time passes, the risk of transmission decreases. Syphilis is a systemic infection, which means that the infection is present throughout the whole body.

Safer sex

A good way to reduce the risk of transmission is to use a condom. Because Syphilis has such a high risk of transmission at the beginning of the infection, there is a high risk that you can get Syphilis when you have other kinds of sex or close contact. Therefore, regular testing is important, especially if you’re a man who have sex with men, so that a Syphilis infection can be detected and treated in time.


Syphilis testing is mainly done through blood test, but you can also do a swab from the entrance wound, if there is one. Testing through blood sample can be done from the crease of the arm or through a small prick in the finger.

It can take up to twelve weeks after the sex before you get a definite answer to a Syphilis test.


Syphilis is cured with antibiotics. Penicillin is usually given with an injection in the thigh/buttock on two occasions with a week in between. Depending on how far the infection has progressed and if you are allergic to penicillin, there are also other treatment options.


Herpes is a virus that infects the neural pathways in the body. Herpes is common and a large part of the population carry the virus, but not everyone gets symptoms. When you have Herpes blisters, the risk of transmitting other STI’s and HIV increases.


The most common symptom is blisters around the mouth or on the genitals. The blisters are not dangerous, but can hurt and be annoying. Usually the blisters come in outbursts that comes and goes, which means that you get blisters that disappear and then are symptom-free for a while and later get new blisters. Between outbursts, the virus is resting in the nerves of the mucous membrane. The blisters can come often or less frequently, and some never get any blisters or only get it occasionally. For many, the blisters usually comes when you have a cold, are stressed or have a weakened immune system.

Some people who get Herpes get a primary infection that makes them sick with fever, pain and swollen lymph nodes. Subsequent relapses tend to be milder. In rare cases, the virus can also attack other parts of the body that require different care and treatment.

Risk of transmission

Herpes is transmitted through contact between mucous membranes, mucosa and skin, as well as via saliva and other body fluids. Herpes can be transmitted even when you don’t have any blisters, but then the risk is lower. The rash is usually on and around the genitals, anus and/or mouth, on or near the border between mucous membrane and normal skin.

If you have a Herpes outbreak when you are about to give birth, Herpes can be transmitted to the baby, and therefore it is good to talk to your midwife during pregnancy if you have Herpes.

Safer sex

The most important way to reduce the risk of transmitting the Herpes virus is to not let the infected mucous membrane come into contact with other mucous membranes when you have or feel like you are about to get blisters. Before the blisters break out, you usually feel a stinging sensation or itch where they later appear. Avoid giving oral sex when you have cold sores. Condoms during anal and vaginal sex reduce the risk of transmission.


To see if someone has Herpes, one usually look for blisters. Therefore, it is best to go to a testing clinic when you have blisters. It is also possible to test for antibodies in the blood, but this is rarely done. The time from sex until you notice you have Herpes is between two and 20 days.

Herpes is a lifelong infection and outbreaks of blisters comes and goes.


Herpes blisters can be treated with virus-suppressing ointment and for those who have major problems with recurring outbreaks of blisters, there are also virus-suppressing tablets.



A Hepatitis infection can cause the skin and the whites of the eyes to turn yellow, but not always. Other symptoms can be fever, fatigue and nausea.

Hepatitis, also called jaundice, is a family of viruses. Hepatitis comes in several different varieties. Hepatitis A, B and C are the most common. The different types of Hepatitis are transmitted in slightly different ways and they are difficult to get.

Testing for Hepatitis is done via a blood test.

Hepatitis A

Hepatitis A is transmitted via faeces and can in some cases be transmitted during sex, e.g. oral sex in and around the anus ( rimming ), but most commonly it is transmitted via contaminated food and water and therefore it is usually not considered a sexually transmitted infection. There is a vaccine against hepatitis A. Hepatitis A usually heals on its own within 3 months and no special treatment is neededf. If you once had hepatitis A, you are immune to hepatitis A for the rest of your life. The infection is particularly common among men who have sex with men, and if you belong to that group, it is therefore a good idea to get vaccinated. After two shots, about six months apart, the body has protection against hepatitis A for up to 30 years.

Hepatitis B

Hepatitis B is transmitted through blood or sex in the same way as HIV. Hepatitis B leads to an infection of the liver. If you have Hepatitis B, the virus is found throughout the body, in blood, semen and mucous membranes. The most effective way to reduce the risk of transmission of Hepatitis B is to use a condom during vaginal and anal sex and to avoid semen in the mouth. You can also use a condom during oral sex to further reduce the risk. Just like Hepatitis A, there is a vaccine against Hepatitis B.

Just over half of everyone who gets Hepatitis B has no symptoms. The most common symptoms are nausea, diarrhea, vomiting and stomach pain. You may also experience muscle and joint pain. After a while, the urine may become darker, the stool lighter, and the skin and whites of the eyes may turn yellow. Hepatitis B usually heals on its own, but around five percent develop a chronic inflammation of the liver, which can lead to liver cancer. If you once had Hepatitis B and it was cured, you are immune to Hepatitis B for the rest of your life.

Men who have sex with men receive the Hepatitis B vaccine free of charge.

Vaccination is done through three injections with some time in between to get full protection. There is a combined vaccine that protects against both Hepatitis A and B. More information about, and access to, vaccination against Hepatitis A and B can be obtained from a primary health center or vaccination clinic. All children born in Sweden are vaccinated against Hepatitis B within the general vaccination programme. However, you must take booster doses for the protection to be complete.

Hepatitis C

Hepatitis C is transmitted through blood, for example if you share syringes with others. Hepatitis C can also be transmitted sexually, but the risk is small.

Hepatitis C usually causes no symptoms. In acute Hepatitis C, you may have yellow-colored skin, nausea and stomach pains. About half of all cases of Hepatitis C lead to chronic inflammation of the liver and can lead to Cirrhosis and liver cancer.

There is effective treatment for Hepatitis C. However, the costs of the drugs are high and not all patients with Hepatitis C get access to treatment.

HPV (human papillomavirus)

HPV comes in many variants and is common. Many types of HPV heal on their own without leaving any traces behind. A majority of everyone with an active sex life will get HPV at some point in their lives. Some types of HPV can lead to genital warts, also known as condylomas.

HPV can cause cell changes that can lead to cervical cancer, penile cancer and anal cancer.


HPV is transmitted through sex and other physical contact. There are over 150 different types of HPV and about 30 of them can infect the genitals, anus and tonsils. If you get condyloma and have a penis, the warts are usually on the foreskin, the glans or the shaft, but they can also be in the opening of the urethra. If you have a vagina, warts can be on the labia, around the urethra and in the vaginal entrance. They can also sit further into the vagina and on the cervix and can then be difficult to detect. You can also get warts in and around the anus. HPV can be transmitted to the mouth and throat. The warts can hurt, but usually they cause no discomfort.

Most types of HPV virus do not cause visible warts. These types of HPV can cause cell changes on and in the cervix, in the anus and in the throat, which can eventually lead to cancer.

Safer sex

To reduce the risk of HPV transmission, it is good to use a condom during anal and vaginal sex. If you have visible condyloma warts, you should avoid having sex where your partner comes into contact with the warts. However, it is difficult to reduce the risk of transmission of HPV.


Most of the time, testing for HPV is done by looking for warts. HPV that does not cause genital warts is difficult to test for. Everyone who has a female social security number and is between the ages of 23 and 60 is regularly called for a pap smear. A pap smear involves taking a sample with a small brush from the cervix at the innermost part of the vagina, which is then analyzed to be able to detect and treat any cell changes in time before they develop into cancer.


Condyloma warts usually disappear on their own after a few months and usually do not need to be treated. If they cause discomfort, they can sometimes be treated with a solution or cream that is applied to the warts. The warts can also be removed surgically.

Good to know

There are vaccines against the HPV types that can cause cell changes and those that cause condyloma. Since 2020, a vaccine has been offered to all children in 5th grade within the general vaccination program for children. The vaccine is most effective if you get it before you start having sex with others.

HPV virus can be transmitted from vagina to vagina. That’s why it’s important that everyone with a vagina, even those who have never had sex with people with a penis, go for regular pap smear. If you have a vagina but are a legal man, you will not receive invitations to take a pap smear, and you must therefore remember to book an appointment for this yourself.

Bacterial vaginosis

Bacterial vaginosis involves foul-smelling discharge from the vagina due to altered bacterial flora. The discharge is often runny and smells bad. It can sting and itch, but is often harmless. Bacterial vaginosis is very common, most people who have a vagina get it at some point in their life and many get it several times.

Bacterial vaginosis is not a sexually transmitted disease, but can occur after having sex.

You usually get it without having had sex. The bacterial flora in the vagina changes when you have your period, if you have sex or for other reasons. Studies are showing that bacterial vaginosis can be sexually transmitted between vaginas. If you have bacterial vaginosis and have a regular partner who also has a vagina, it may therefore be a good idea for your partner to also go to the gynecologist and get checked so that you can receive treatment at the same time. Bacterial vaginosis is treated with antibiotics.

Yeast infection

A yeast infection in the vagina means that the natural yeast in the vagina has multiplied too much and causes itching and irritation. Sometimes you may have a white curd-like discharge. Yeast infections are harmless but annoying. Most people who have a vagina gets a yeast infection at some point in their life, some get it many times. Treatment is available both over-the-counter at a pharmacy and with a prescription. Yeast infections are uncommon among people with a penis.

Urinary tract infection (UTI)

Urinary tract infection is common in people who have a vagina. It is treated with antibiotics. People with penises rarely get urinary tract infections because they usually have longer urethras and bacteria can’t get up to the bladder. The most common symptom of a urinary tract infection is that it stings and hurts when you urinate. A UTI is not an STI, but you can get a UTI after having sex because friction against the opening of the urethra can make it easier for bacteria to get in there.