Skip to main content

Health condition · Clinically reviewed

Orchitis, and why torsion always gets ruled out first.

Sudden testicular pain and swelling has more than one cause. Same-day assessment separates a urological emergency from an infection that treats well.

Jump to treatment
A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE CKS, BASHH and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance on same-day torsion exclusion, STI screening and antibiotic choice.

Key facts

Orchitis at a glance.

The essentials, in plain English - what it is, what causes it, and how it's assessed and treated in the UK today.

  • What it is

    Inflammation of the testicle - usually one-sided, causing pain, swelling and tenderness of the scrotum.

  • Main causes

    Viral (commonly mumps) or bacterial, often as part of epididymo-orchitis spreading from the epididymis.

  • Who gets it

    Mumps orchitis affects post-pubertal males after mumps; bacterial cases follow STIs in younger men or urinary infections in older men.

  • The urgent question

    Every case must have testicular torsion excluded first - it is a time-critical surgical emergency, not orchitis, until proven otherwise.

  • Fertility risk

    Bilateral mumps orchitis can cause testicular atrophy and reduced fertility - unilateral cases rarely affect fertility.

  • Treatment shape

    Antibiotics for bacterial or STI-related cases, supportive care for viral orchitis, analgesia and scrotal support throughout.

Why this guide matters

Sudden testicular pain deserves a same-day answer.

Orchitis usually treats well once diagnosed. The three points below explain why getting there quickly and safely matters so much.

  • Torsion must be excluded first

    Testicular torsion can look like orchitis in its early hours - any doubt means an urgent surgical opinion, not a wait-and-see approach.

  • The cause changes the treatment

    Viral mumps orchitis needs supportive care alone, while bacterial and STI-related cases need the right antibiotic, promptly.

  • Bilateral cases need extra care

    When both testicles are affected by mumps orchitis, fertility follow-up matters - most unilateral cases recover fully.

How the diagnosis is made

From sudden pain to a confirmed cause.

The steps a UK GP, sexual health clinic or emergency department will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Same-day urgent assessment

    Any acute testicular pain needs same-day review - speed of onset and age help distinguish orchitis from torsion.

  2. 02

    Assessing

    Exclude testicular torsion

    Cremasteric reflex, onset speed and examination findings are checked. If there is any doubt at all, this is treated as a urological emergency.

  3. 03

    Assessing

    History and exposure review

    Recent mumps or parotitis, sexual history, urinary symptoms and any prior epididymitis are all relevant to the likely cause.

  4. 04

    Confirming

    Urine dipstick and MSU

    A urine sample checks for infection and helps identify urinary pathogens, particularly in older men.

  5. 05

    Confirming

    STI screen (NAAT)

    A nucleic acid amplification test for chlamydia and gonorrhoea when a sexually acquired cause is suspected.

  6. 06

    Confirming

    Scrotal ultrasound with Doppler

    Assesses blood flow to exclude torsion and an abscess, and confirms inflammation within the testicle and epididymis.

  7. 07

    Preparing

    Mumps serology if indicated

    When a viral cause is suspected, mumps IgM/IgG confirms recent infection and rules out a bacterial cause needing antibiotics.

Typical timeline: same-day assessment, with results and a treatment plan usually within 24 to 48 hours.

Symptoms

What orchitis actually feels like.

The classic mix of pain, swelling and tenderness on one side. And the features that mean it's time to seek emergency care instead.

  • Testicular pain

    Usually gradual over hours to a day or two - a sudden, severe onset should raise suspicion of torsion instead.

  • Scrotal swelling

    The affected testicle feels heavier and larger, often with a visibly swollen scrotum on that side.

  • Tenderness

    The testicle and often the epididymis behind it are tender to touch, sometimes severely so.

  • Scrotal erythema and warmth

    The overlying skin can look red and feel warm - a sign of active inflammation.

  • Fever and feeling unwell

    Bacterial epididymo-orchitis often brings a fever, chills and general malaise alongside local symptoms.

  • Recent mumps parotitis

    Viral orchitis typically follows mumps parotid swelling by four to eight days, though it can occur without it.

  • Urethral discharge or dysuria

    Discharge, pain passing urine or urinary frequency point towards an STI or urinary tract cause.

  • Red flag - sudden severe onset

    Sudden, severe pain with a high-riding or horizontal testicle needs emergency assessment for torsion, not an orchitis work-up.

Treatment

How orchitis is treated in the UK.

Torsion excluded first, then a cause-led plan - antibiotics where bacterial, supportive care where viral, and surgery where needed.

  • Emergency urological referral

    If torsion cannot be confidently excluded, immediate surgical exploration takes priority over any orchitis treatment.

  • Antibiotics for STI-related cause

    Typically covering chlamydia and gonorrhoea per BASHH guidance in younger, sexually active men - chosen after or alongside the NAAT test.

  • Antibiotics for urinary-pathogen cause

    A different antibiotic choice targets coliform organisms, more common in older men with urinary tract involvement.

  • Analgesia

    Regular paracetamol and an NSAID such as ibuprofen control pain and inflammation effectively for most patients.

  • Scrotal support

    A supportive jockstrap or snug underwear, plus rest, reduces movement-related pain while inflammation settles.

  • Partner notification and treatment

    When an STI is confirmed, sexual partners need testing and treatment, and the case should be notified per local sexual health pathways.

  • Supportive care for mumps orchitis

    No specific antiviral exists - rest, analgesia and scrotal support while the immune system clears the infection.

  • Abscess drainage

    If a scrotal abscess develops, it needs surgical or radiological drainage alongside continued antibiotics.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or sexual health clinic knows your history and can tell you which parts apply to you. If in doubt, get seen the same day.

  • NICE Clinical Knowledge Summaries (CKS). Epididymitis and epididymo-orchitis.

  • British Association for Sexual Health and HIV (BASHH). UK guideline for the management of epididymo-orchitis.

  • UK Health Security Agency (UKHSA). Mumps: guidance, data and analysis.

  • European Association of Urology (EAU). Guidelines on urological infections.

Red flags

When to seek emergency care.

Most orchitis is manageable once diagnosed. These are the situations that need an emergency department or urgent urology review instead.

  • Suspected testicular torsion

    Sudden severe pain, a high-riding or horizontal testicle, or an absent cremasteric reflex - this is a surgical emergency needing immediate urology assessment, any delay risks losing the testicle.

  • Torsion of a testicular appendage mimicking orchitis

    Can look similar clinically - ultrasound and urgent review still apply whenever torsion cannot be confidently excluded on examination alone.

  • Scrotal abscess

    Fluctuant swelling, worsening pain or spiking fevers despite antibiotics suggest abscess formation needing surgical drainage.

  • Sepsis or systemic illness

    High fever, rigors, confusion or a fast heart rate alongside scrotal pain need urgent same-day hospital assessment.

  • Bilateral mumps orchitis

    Involvement of both testicles carries a real risk of subfertility - needs careful follow-up and fertility counselling.

  • Testicular atrophy on follow-up

    A testicle that shrinks in the weeks after orchitis should be reviewed, particularly when fertility is a concern.

  • Recurrent or treatment-resistant infection

    Symptoms not settling after an appropriate antibiotic course need re-assessment, repeat imaging and consideration of an alternative diagnosis.

  • Underlying urological abnormality

    Recurrent epididymo-orchitis in older men can point to an underlying prostate or bladder outflow problem worth investigating.

  • Testicular tumour masquerading as orchitis

    A firm, painless or persistent lump that does not resolve with treatment should be re-examined and, if in doubt, imaged again to exclude a tumour.

Living with it

A short illness, with a clear recovery path.

Four things that make the biggest difference while you recover - rest, support, follow-up and, for bilateral mumps cases, fertility reassurance.

A quiet reminder

Most cases settle fully within one to two weeks.

Pain and swelling ease steadily once the right treatment is started - patience and rest do the rest.

  1. 01 Rest

    Give it proper rest

    Bed rest and reduced activity for the first few days ease pain and help the swelling settle faster.

  2. 02 Support

    Wear supportive underwear

    A snug jockstrap or briefs reduce movement of the testicle and noticeably cut down on discomfort.

  3. 03 Follow-up

    Attend your follow-up review

    Confirming the swelling and tenderness have resolved matters, especially after a bacterial or STI-related episode.

  4. 04 Fertility

    Ask about fertility if bilateral

    If both testicles were affected by mumps orchitis, a semen analysis some months later can put your mind at rest or flag a problem early.

Frequently asked

Everything we get asked about orchitis.

Quick answers on torsion, mumps, fertility and antibiotics.

  • What is orchitis?

    Orchitis is inflammation of the testicle, causing pain, swelling and tenderness, usually on one side. It is most often viral - typically mumps - or bacterial, frequently occurring alongside inflammation of the epididymis as epididymo-orchitis.

  • How is orchitis different from testicular torsion?

    Torsion is a sudden twisting of the testicle that cuts off its blood supply and is a surgical emergency, while orchitis is inflammation that develops more gradually. Because they can look similar early on, every case of acute testicular pain is assessed urgently to exclude torsion first.

  • Can mumps cause orchitis?

    Yes - mumps orchitis affects around one in five post-pubertal males who catch mumps, usually starting four to eight days after the parotid glands swell. It can occasionally occur without obvious parotitis.

  • Does orchitis affect fertility?

    Unilateral orchitis rarely causes lasting fertility problems. Bilateral mumps orchitis carries a higher risk of testicular atrophy and reduced sperm count, so fertility counselling and follow-up semen analysis are recommended in those cases.

  • Is orchitis a sexually transmitted infection?

    Orchitis itself is not an STI, but bacterial epididymo-orchitis in younger, sexually active men is often caused by chlamydia or gonorrhoea. An STI screen and partner notification are part of standard care when this is suspected.

  • What happens if orchitis is left untreated?

    Untreated bacterial orchitis can progress to a scrotal abscess, chronic pain or, in bilateral mumps cases, reduced fertility. Prompt assessment and the right antibiotics or supportive care usually lead to full recovery within one to two weeks.

Related content

Keep reading.

Pulse Healthcare concierge

Send us your enquiry

A concierge service for UK private healthcare. We match you with the best vetted clinics and consultants in our network - they then contact you directly.

So we can match you to the right clinician close to you.

We reply to every enquiry within 24 hours (Mon–Fri). Confidential - your details are never shared outside our vetted consultant network.