Can you catch a Shigella infection from sexual activity, and what are the signs?

Concerns about symptoms following sexual activity are entirely understandable, and it is worth knowing that not every symptom automatically indicates an STI. Shigella is one infection that can spread through sexual contact, though it is not always immediately recognised as a sexually transmissible condition. Understanding what Shigella is, how it may be passed on, and what signs to look out for can help you make an informed decision about testing.

Our clinic provides confidential STI testing services. We do not provide GP services or dermatology consultations, but we can advise on appropriate next steps if further medical care is needed.

Quick Answer: Can Shigella Be Passed On Through Sex?

Yes, a Shigella infection can be transmitted through sexual activity, particularly through oral-anal contact or any sexual activity involving indirect contact with faecal matter. Symptoms may include severe diarrhoea, stomach cramps, nausea, and fever. However, these symptoms can have several possible causes, and symptoms alone cannot confirm Shigella or any other infection.

Signs that may be associated with Shigella can include:

• Sudden, severe diarrhoea (sometimes with blood or mucus)
• Stomach cramps and abdominal pain
• Nausea or vomiting
• Fever
• Urgent need to use the toilet
• General fatigue or feeling unwell

Symptoms alone cannot confirm a Shigella infection or any other cause. Testing may help provide clarity.

When Could Gastrointestinal Symptoms Be Linked to Sexual Activity?

Gastrointestinal symptoms following sexual contact are not always recognised as potentially linked to an infection passed during sex. In some cases, symptoms such as diarrhoea, cramping, and nausea may arise within one to four days of exposure to Shigella bacteria. If you have had oral-anal or anal sexual contact and develop these symptoms, it may be worth considering whether a sexually transmitted gut infection could be a factor, alongside other possible explanations.

Section 1: Understanding Shigella

Shigella is a bacterial infection of the gut caused by the Shigella group of bacteria. It is one of the more common causes of bacterial gastroenteritis in the UK. Traditionally associated with contaminated food or water, it is increasingly recognised as a sexually transmissible infection, particularly among men who have sex with men (MSM), though it can affect anyone.

The infection is highly contagious. Even a very small number of bacteria can cause illness, which is why it can spread so readily through certain types of sexual activity. Importantly, many people who contract Shigella may not immediately connect their symptoms to sexual exposure.

Section 2: Common Non-Sexual Causes of Similar Symptoms

It is important to note that the symptoms associated with Shigella — including diarrhoea, stomach cramps, nausea, and fever — can have several possible causes entirely unrelated to sexual activity:

• Food poisoning from contaminated food or drink
• Norovirus or other viral gastroenteritis
• Traveller's diarrhoea following travel abroad
• Irritable bowel syndrome (IBS) flare-ups
• Dietary changes or food intolerances
• Other bacterial infections such as Campylobacter or Salmonella

Because these conditions can present with very similar symptoms, testing may help clarify the cause rather than relying on symptoms alone.

Section 3: Situations Where Symptoms May Appear

Gastrointestinal symptoms can arise in a variety of everyday contexts and do not always indicate infection:

• After eating unfamiliar food or dining out
• Following periods of stress or anxiety, which can affect gut function
• After travel, particularly to regions with different food hygiene standards
• Following antibiotic use, which can temporarily disrupt gut bacteria
• After sexual activity, particularly oral-anal contact, where bacterial transmission is possible

Understanding the context in which symptoms develop may help inform your decision about whether testing is appropriate.

Section 4: STIs and Gut Infections That May Cause Similar Symptoms

Several infections — both gastrointestinal and sexually transmitted — can present with overlapping symptoms. These may include:

• Shigella – bacterial gut infection transmissible through sexual contact
• Gonorrhoea – can cause rectal symptoms including discharge and discomfort
• Chlamydia – rectal chlamydia can cause discomfort, though often has no symptoms
• Giardia – a parasitic infection with similar gastrointestinal presentation
• Hepatitis A – transmissible through oral-anal contact, causing liver inflammation and flu-like symptoms

It is worth noting that many infections — including sexually transmitted ones — can cause mild symptoms or none at all. This is one reason why targeted testing is often more reliable than symptom assessment alone.

Section 5: Why Symptoms Alone Cannot Confirm the Cause

Many gastrointestinal symptoms look and feel similar regardless of their underlying cause. Diarrhoea, cramping, and nausea are non-specific symptoms that can result from a wide range of conditions. Even healthcare professionals cannot diagnose the cause of these symptoms from their presentation alone — laboratory testing is required to identify the specific bacteria, virus, or parasite responsible.

This is why clinical testing is such a valuable tool. It provides objective information that symptoms simply cannot.

Section 6: When STI or Infection Testing May Be Sensible

There are certain situations where seeking testing may be a reasonable and sensible step:

• You have had oral-anal or anal sexual contact and developed gastrointestinal symptoms within one to four days
• You have a new or casual sexual partner
• A recent sexual partner has been diagnosed with Shigella or another infection
• Your symptoms are persistent, severe, or worsening
• You are experiencing rectal discomfort, discharge, or bleeding alongside gastrointestinal symptoms
• You have had unprotected sexual contact and are concerned about exposure

Section 7: How Testing for Shigella and Related Infections Works

Testing for Shigella typically involves a stool sample, which is analysed in a laboratory to identify the presence of Shigella bacteria. Depending on your circumstances and symptom profile, a clinician may also recommend:

• Rectal swabs to check for gonorrhoea, chlamydia, or other rectal STIs
• Blood tests for infections such as Hepatitis A or HIV
• Urine tests where relevant

A full STI screen can provide broader reassurance if you have had potential exposure to multiple infections. Results from laboratory analysis are typically returned confidentially and securely.

Section 8: When Symptoms Are Less Likely to Be Shigella

Not every bout of diarrhoea or stomach upset following sexual activity indicates Shigella or any sexually transmitted infection. Temporary gastrointestinal upset can occur due to:

• Mild dietary changes or unfamiliar food consumed around the time of sexual activity
• Anxiety or stress responses affecting gut motility
• A short-lived viral illness unrelated to sexual contact
• Normal variation in digestive function

If symptoms resolve quickly and there is no clear exposure risk, it is possible that the cause is entirely unrelated to sexual activity.

Section 9: Frequently Asked Questions

Can Shigella really be passed on through sex?

Yes. Shigella can be transmitted through oral-anal contact or any sexual activity involving indirect contact with small amounts of faecal matter. It does not require penetrative sex to spread.

Do Shigella symptoms always appear immediately?

Not necessarily. Symptoms typically develop within one to four days of exposure, though this can vary between individuals.

Should I get tested even if my symptoms have resolved?

It is worth discussing this with a healthcare provider. Some infections can persist without symptoms even after an initial illness resolves. Testing may still be appropriate depending on your exposure history.

Is Shigella the same as a standard STI?

Shigella is classified as a gastrointestinal infection, but it is increasingly recognised as sexually transmissible. It differs from classic STIs such as chlamydia or gonorrhoea but can be passed on through sexual activity in a similar way.

Can I test for Shigella alongside STIs?

Yes. Depending on your symptoms and exposure history, combined testing may be appropriate. A full STI screen alongside a stool test can provide a broader picture.

How common is sexually transmitted Shigella in the UK?

Rates of sexually transmitted Shigella have increased in the UK in recent years, particularly among MSM communities. Public Health England has issued guidance recognising it as a significant concern within sexual health settings.

Section 10: When to Seek Medical Advice

Certain symptoms should prompt you to seek advice from an appropriate healthcare service promptly:

• Severe or bloody diarrhoea lasting more than three days
• High fever alongside gastrointestinal symptoms
• Signs of dehydration (dizziness, reduced urination, extreme thirst)
• Rectal bleeding or significant pain
• Symptoms that are worsening rather than improving

If symptoms persist or worsen, consultation with an appropriate healthcare service — such as your GP, NHS 111, or a sexual health clinic — may be advised.

Confidential STI Testing in the UK

If you are concerned about possible exposure to Shigella or other infections following sexual activity, confidential testing appointments are available at STIC Clinic. Testing decisions depend on symptoms, exposure history, and individual risk factors. Our team can help advise on which tests may be most relevant to your circumstances.

You may also wish to explore specific testing options, including chlamydia testing, gonorrhoea testing, and syphilis testing, depending on your recent sexual history.

Medical Disclaimer: This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Sexual health concerns should be assessed based on individual circumstances. If you are experiencing persistent, severe, or worsening symptoms, consultation with an appropriate healthcare service is advised. Our clinic provides private STI testing services only.