Can STIs cause diarrhoea?

Diarrhoea is loose, watery, and frequent passage of stool that may also be accompanied by other symptoms, such as:

• Lower abdominal pain
• Bloating
• Nausea
• Vomiting
• Fever
• Bloody stool
• Mucus in the stool
• An urgent need to defecate

Acute diarrhoea

Most cases of diarrhoea are acute. In these cases, diarrhoea results from your body’s response to certain foods, viruses, bacteria, and other foreign agents.

Common causes of diarrhoea include:

• Viral infections (the flu, norovirus, rotavirus, etc)
• Bacterial infections (e.coli, c. difficile, etc)
• Medicines, including many antibiotics and antiviral medications
• Fructose, which can be found in many fruits and honey
• Artificial sweeteners

These cases of diarrhoea are usually temporary and go away once the underlying cause is corrected (i.e., the infection passes or is cured, or any foods you ingest are changed).

Chronic diarrhoea

Chronic diarrhoea, often caused by digestive disorders, may require treatment or lifestyle changes. Chronic diarrhoea is a common symptom of:

• Irritable bowel syndrome (IBS)
• Crohn’s Disease
• Pancreatitis
• Colitis
• Food intolerances

While many people may not associate diarrhoea with sexually transmitted infections, there may occassionally be a link. .

Here are a few infections that can cause or are associated with diarrhoea.

HIV

Human Immunodeficiency Virus (HIV) damages the immune system by compromising your body’s ability to produce T-cells. If left untreated, HIV can progress slowly over several years and develop into AIDS.

Although most people with HIV will not have any symptoms for years and years, diarrhoea is one of the most common symptoms of an HIV infection. The severity of the diarrhoea can vary from person to person. It can appear during an acute HIV infection in the first few days and weeks. Other symptoms of an acute HIV infection include:

• Fever
• Nausea
• Night sweats
• Headaches
• Joint pain
• Sore throat
• Swollen lymph nodes

Diarrhoea can also be caused by HIV medications. Antiretroviral medications, which are often used to treat HIV, often carry a risk of diarrhoea.

People with HIV also commonly experience gastrointestinal problems, resulting from a compromised immune system. Common gastrointestinal problems during HIV include:

• Intestinal infections due to unusual bacteria and parasites that we coul not see in someone HIV negative
• Bacterial overgrowth within the digestive tract
• HIV enteropathy

Gonorrhoea

Gonorrhoea is a bacterial STI transmitted through unprotected vaginal, anal, or oral sex.

While Gonorrhoea infections are most common in the genital area, it’s possible to get the infection in your rectum. This usually results from unprotected anal sex and sharing sex toys.

People with an anal Gonorrhoea infection may experience proctitis, an inflammation of the rectum that is associated with rectal fullness, deep rectal or anal pain, sometimes with painful bowel movements, and often with mucous or bloody discharge from the rectum.

When a patient has blood and mucous in the stool and an urgent need to pass stool, quite a good part of the rectum will be infected and in this case, there may be diarrhoea too.

Chlamydia

Like Gonorrhoea, you can also get a Chlamydia infection in your rectum, also through unprotected anal sex and sharing sex toys.

A Chlamydia infection in the rectum can result in similar symptoms of proctitis, including inflammation and pain around the rectum, painful bowel movements, and unusual discharge from the anus (mucous and blood staining).

Like with Gonorrhoea, Chlamydia can cause watery stools. However, it will cause the same irritation and urgent need to defecate.

The very unusual “Super Chlamydia”· called lymphogranuloma venereum that we see in people sharing anal sex toys is more likely to produce more sever symptoms, including constipation or diarrhoea.

Herpes

Like with the above examples, getting an anal Herpes infection in your rectum can result in diarrhoea in people with severe inflammatory bowel disease (like Crohn’s disease or ulcerative colitis).

HSV colitis is a rare but severe complication of inflammatory bowel syndrome (IBS). Immunosuppressant drugs are often used to treat IBS, and the reduced immune function can leave certain patients at risk for developing opportunistic infections.

An anal HSV infection, contracted by someone with IBS, can exacerbate GI symptoms, causing watery stool, blood in stool, abdominal pain, fever, and nausea.

Shigella

Shigella is an infection caused by bacteria that commonly causes diarrhoea, where water may be infected.

Several outbreaks have been seen, especially in men who have sex with men, where the infection was spread orally through anal-oral contact. This bacteria produces profuse diarrhoea and rapid dehydration and weight loss.

Having diarrhoea doesn’t necessarily mean you’ve contracted an STI. Due to the complexity of these infections, diagnosing an STI based on a single symptom is nearly impossible.

However, if you experience diarrhoea, it may indicate an STI. In such cases, getting tested is essential to ensure your health and well-being.

Get tested for HIV, Chlamydia, Gonorrhoea, Syphilis, and Herpes with Better2Know. Book a test at a sexual health clinic near you or get tested from the comfort of your own home with our wide range of Home Test Kits.

This article has been medically reviewed by Dr. Steve Chapman, 03/12/2024.