Orchitis

Orchitis is inflammation of one or both testicles, most often caused by an infection. It can cause testicular pain, swelling, redness, fever, and tenderness, and it matters because some cases can affect comfort, sexual health, and fertility—especially if treatment is delayed or both testicles are involved. Orchitis may occur on its own, but it is also commonly linked with epididymitis (inflammation of the epididymis), in which case doctors may use the term epididymo-orchitis.

For men researching symptoms, testicular infections, or fertility concerns, the key point is this: new testicular pain or swelling should be medically assessed promptly. Orchitis is treatable, but it can sometimes mimic more urgent conditions such as testicular torsion, which is a surgical emergency.

Key takeaways

Orchitis means inflammation of the testicle, usually due to infection.
It can be caused by viral infections such as mumps or by bacterial infections, including sexually transmitted infections in some cases.
Common symptoms include testicular swelling, pain, tenderness, redness, and fever.
Orchitis may happen alone, but many men actually have epididymo-orchitis.
Sudden severe testicular pain is not something to wait on because it can also be testicular torsion.
Treatment depends on the cause and may include antibiotics, rest, pain relief, scrotal support, and follow-up.
Some cases, especially severe or bilateral orchitis, may affect sperm production and fertility.
Prompt medical evaluation improves comfort, lowers complication risk, and helps protect reproductive health.

What is orchitis?

Orchitis is the medical term for inflammation of a testicle. The inflammation may affect one testicle or, less commonly, both. The testicles are responsible for producing sperm and making much of the body’s testosterone, so inflammation in this area is clinically important even when symptoms improve quickly.

In practice, orchitis can develop in two main ways:

Viral orchitis, classically associated with mumps
Bacterial orchitis, often linked with a urinary tract infection, prostate infection, or an STI-related infection that spreads through the reproductive tract

Because the epididymis sits right behind the testicle and stores and transports sperm, infection often involves both structures. That’s why many men diagnosed with “orchitis” are really dealing with epididymo-orchitis.

At a glance

Feature	Orchitis
What it is	Inflammation of one or both testicles
Common causes	Viral infection, bacterial infection, STI-associated infection, spread from epididymitis
Main symptoms	Testicular pain, swelling, tenderness, fever, redness, heaviness
Why it matters	Can mimic emergencies and may affect sperm production or fertility in some cases
How it’s diagnosed	History, physical exam, urine testing, STI testing, and often scrotal ultrasound
Treatment	Depends on cause; may include antibiotics, pain relief, rest, scrotal support, and follow-up

Why orchitis matters in men’s health and fertility

Orchitis is more than a temporary sore testicle. The reason doctors take it seriously is that the testicle is a delicate organ involved in sperm production and hormone function. Significant inflammation can disrupt the environment sperm need to develop well. In some cases, especially if inflammation is severe, prolonged, recurrent, or affects both testicles, there may be a risk of:

Reduced sperm count
Impaired sperm motility or quality
Testicular atrophy (shrinkage of the testicle)
Temporary or, less commonly, longer-lasting fertility issues
Abscess formation or chronic pain in complicated bacterial cases

That does not mean every case of orchitis causes infertility. Many men recover fully. But if someone is trying to conceive, has bilateral symptoms, or notices ongoing changes after infection, follow-up may be worthwhile, sometimes including a semen analysis.

Causes of orchitis

Orchitis is usually caused by infection, but the exact source varies by age, sexual history, and overall health.

1. Viral orchitis

The best-known viral cause is mumps. Mumps orchitis can occur after swelling of the salivary glands, although the timing and presentation can vary. Since widespread vaccination, mumps-related orchitis is less common in many countries but still occurs.

Other viruses may also contribute to testicular inflammation, though mumps remains the classic board-style association.

2. Bacterial orchitis

Bacterial orchitis often happens when an infection spreads from nearby parts of the urinary or reproductive tract, especially the epididymis. Possible bacterial sources include:

Sexually transmitted infections such as chlamydia or gonorrhea, particularly in younger sexually active men
Urinary tract infections
Prostatitis
Bladder outlet obstruction or urinary retention in older men
Recent catheter use or instrumentation of the urinary tract
Anatomical urinary tract abnormalities

3. Epididymo-orchitis

In many cases, the infection starts in the epididymis and then spreads to the testicle. This is called epididymo-orchitis and is one of the most common real-world scenarios behind a painful swollen testicle.

Risk factors

Not being vaccinated against mumps
Recent viral illness
Unprotected sex or STI exposure
History of UTIs or prostate infections
Urinary tract procedures or catheterization
Structural urinary tract problems
Older age with prostate enlargement causing urinary issues

Symptoms and signs of orchitis

Symptoms can range from mild discomfort to significant pain and swelling. Common symptoms include:

Testicular pain, often on one side but sometimes both
Swelling of the testicle
Tenderness to touch
Scrotal redness or warmth
A feeling of heaviness in the scrotum
Fever and chills
Pain with urination if a urinary infection is involved
Urethral discharge if an STI is part of the picture
Pain with ejaculation in some cases
General malaise or body aches, especially with viral illness

Viral orchitis may follow a recent infection and be accompanied by fever and systemic symptoms. Bacterial orchitis may be more likely to come with urinary symptoms, painful urination, or STI-related findings.

What orchitis pain can feel like

Men often describe orchitis pain as aching, throbbing, pulling, or pressure-like. Some cases feel gradual and build over hours to days. However, sudden severe pain should never be assumed to be orchitis, because torsion must be ruled out quickly.

What’s normal vs what’s not?

Minor awareness of the testicles after exercise, prolonged sitting, or minor strain can happen. True orchitis usually involves more than vague discomfort.

Finding	May be less concerning	Needs prompt medical assessment
Mild transient soreness	Brief discomfort that resolves and no swelling	Pain lasting, worsening, or returning repeatedly
Swelling	No true swelling	Visible or increasing testicular/scrotal swelling
Skin changes	No redness or warmth	Red, warm, inflamed scrotal skin
General symptoms	No fever, no illness symptoms	Fever, chills, nausea, or feeling unwell
Urinary or sexual symptoms	None	Burning urination, discharge, STI exposure, painful ejaculation
Pain timing	Mild and improving	Sudden severe pain or rapidly worsening pain

The especially important red flag is sudden onset of severe testicular pain. That pattern raises concern for testicular torsion, which requires emergency care because blood flow to the testicle may be cut off.

How orchitis is diagnosed

Diagnosis starts with a clinical history and exam. Because several conditions can look similar, the goal is not just to identify inflammation but also to determine the cause and to rule out emergencies.

What a clinician may ask about

When the pain or swelling started
Whether symptoms came on suddenly or gradually
One-sided vs both-sided symptoms
Recent viral illness, including mumps exposure
Urinary symptoms such as burning, urgency, frequency, or blood in urine
Sexual history and possible STI exposure
History of trauma
Fever, chills, nausea, or vomiting
Previous testicular problems

Physical examination

The exam may assess:

Location of tenderness
Degree of swelling
Skin redness or warmth
Whether the epididymis is also inflamed
Signs more concerning for torsion, hernia, or another diagnosis

Common tests

Urinalysis and urine culture to look for infection
STI testing, often for chlamydia and gonorrhea when appropriate
Scrotal ultrasound with Doppler to assess blood flow and help distinguish orchitis from torsion
Blood tests in selected cases, especially if there is fever or concern for systemic infection

Why ultrasound is often important

A scrotal ultrasound is commonly used when the diagnosis is unclear or when torsion needs to be excluded. Orchitis often shows an inflamed, enlarged testicle with increased blood flow, whereas torsion may show reduced or absent blood flow. Ultrasound is not perfect in every scenario, but it is a widely used and valuable tool.

Orchitis vs other causes of testicular pain

Testicular pain is a symptom, not a diagnosis. Orchitis is one cause, but not the only one.

Condition	Typical pattern	Why it matters
Orchitis	Inflamed testicle, swelling, pain, sometimes fever; may follow infection	Needs treatment and follow-up to prevent complications
Epididymitis	Pain often starts in the epididymis and may radiate; gradual onset is common	Often bacterial; can spread and become epididymo-orchitis
Testicular torsion	Sudden severe pain, often nausea/vomiting, high-riding testicle	Medical emergency; delayed care can lead to loss of the testicle
Hydrocele	Fluid-filled swelling, often less painful	Usually not an infection but should be evaluated if new
Varicocele	Dull ache or heaviness, often worse standing; “bag of worms” feel	Can affect fertility in some men
Inguinal hernia	Groin/scrotal bulge, discomfort with lifting or straining	Can mimic scrotal conditions
Testicular tumor	Often painless lump, but some cases cause heaviness or discomfort	Any new lump needs assessment

One of the biggest mistakes men make is assuming that all testicular pain is “just an infection.” It isn’t. That’s why same-day assessment is recommended for new, significant, or unexplained swelling or pain.

Treatment for orchitis

Treatment depends on the underlying cause. The core goals are to treat infection if present, control pain and swelling, and prevent complications.

If orchitis is bacterial

Bacterial orchitis is usually treated with antibiotics. The exact regimen depends on the suspected source:

STI-related infections may require antibiotics targeted to common sexually transmitted bacteria
Urinary tract-related infections are treated based on likely urinary pathogens and sometimes culture results

It is important to complete the full prescribed antibiotic course, even if symptoms improve early.

If orchitis is viral

Viral orchitis does not respond to antibiotics unless there is also a bacterial infection. Management is usually supportive and may include:

Rest
Anti-inflammatory medication or other pain relief, if a clinician says it is safe for you
Scrotal support, such as supportive underwear
Cold packs wrapped in cloth for short periods
Hydration and symptom monitoring

General self-care measures

Rest and limit strenuous activity.
Support the scrotum with snug underwear or an athletic supporter.
Use pain relief as advised by a clinician.
Avoid sex until evaluated and until an STI or contagious cause has been addressed.
Follow instructions for testing, treatment, and follow-up.

If an STI is involved

When orchitis or epididymo-orchitis is linked to an STI:

Sexual partners may need testing and treatment
Sex should be avoided until treatment is complete and a clinician says it is safe to resume
Retesting may be recommended depending on the infection

When hospitalization may be needed

Most cases can be managed as an outpatient, but hospitalization is sometimes needed for:

Severe pain or systemic illness
High fever
Concern for abscess or complications
Inability to keep down oral medications
Need for urgent imaging or specialist input

Can orchitis affect fertility?

Yes, it can—though not in every case. The effect depends on severity, cause, duration, and whether one or both testicles are involved.

How orchitis may impact sperm production

The testicles produce sperm in a tightly regulated environment. Infection and inflammation can:

Disrupt sperm-making tissue
Raise local temperature
Trigger oxidative stress and inflammatory damage
Cause swelling that affects normal testicular function
Lead to scarring or atrophy in some cases

Who may need fertility follow-up?

Follow-up may be especially reasonable for men who:

Had bilateral orchitis (both testicles)
Had severe swelling or prolonged symptoms
Notice testicular shrinkage afterward
Are actively trying to conceive
Already had low sperm counts or known fertility issues before the illness

Should you get a semen analysis after orchitis?

Not everyone needs one, but it may be helpful if you are trying for pregnancy or are concerned about fertility after a significant episode. A semen analysis can assess sperm concentration, motility, morphology, and volume. Because sperm development takes time, testing is often more informative weeks to months after recovery rather than during the acute illness.

Can orchitis lower testosterone?

Most men do not develop obvious long-term testosterone problems after a straightforward, treated episode affecting one testicle. But severe bilateral damage could theoretically impair hormone production. If symptoms such as persistent fatigue, low libido, erectile changes, or loss of muscle mass occur after a serious infection, medical follow-up may be appropriate.

Recovery, healing, and long-term outlook

Many men improve with appropriate treatment and recover without major long-term issues. Pain often starts getting better before swelling fully resolves. In some cases, tenderness or fullness may take longer to settle than expected.

Typical recovery points

Pain may begin to improve within days of proper treatment
Swelling can take longer to go down
Residual tenderness may persist for a while even after infection is improving
Follow-up may be needed if symptoms do not clearly improve

Possible complications

Complications are not inevitable, but they can occur, especially with delayed treatment or severe infection. These may include:

Abscess
Chronic scrotal pain
Testicular atrophy
Reduced fertility
Recurrent infection if an underlying cause remains untreated

Signs recovery is not going as expected

Worsening pain after starting treatment
Persistent high fever
New redness spreading across the scrotum
Nausea or vomiting with escalating pain
No meaningful improvement after a few days
A new lump that remains after inflammation settles

When to see a doctor urgently

You should seek urgent medical care for any new testicular swelling or pain, especially if symptoms are pronounced. Immediate assessment is especially important if you have:

Sudden severe testicular pain
Nausea or vomiting with scrotal pain
Rapid swelling
Fever and feeling very unwell
Scrotal redness and warmth that are worsening
Recent STI exposure or urethral discharge
A testicular lump or persistent swelling after treatment

If there is any chance the problem is torsion, time matters. Waiting to “see if it passes” is the wrong move.

Questions to ask your doctor

If you’ve been told you may have orchitis, these questions can help you get clear next steps:

Do you think this is orchitis, epididymitis, or epididymo-orchitis?
Do I need an ultrasound to rule out torsion or another problem?
What do you think caused it: viral, bacterial, urinary, or STI-related?
Do I need urine testing or STI testing?
If I’m taking antibiotics, when should I expect improvement?
When is it safe to resume sex, exercise, or work?
Could this affect fertility, and should I consider a semen analysis later?
Do I need follow-up if the swelling doesn’t fully go away?
Should my partner be tested or treated?
What warning signs mean I should come back urgently?

Frequently asked questions

Is orchitis an STD?

Not always. Orchitis can be caused by viruses such as mumps or by bacteria from the urinary tract. Some cases are linked to sexually transmitted infections, especially when epididymitis is also present.

Can orchitis go away on its own?

Some viral cases may improve with supportive care, but you should not assume testicular pain is harmless. Medical evaluation is important because bacterial infection may require antibiotics and torsion must be ruled out.

How long does orchitis last?

The timeline varies by cause and severity. Pain may improve within days with treatment, but swelling and tenderness can take longer to fully resolve.

Can orchitis cause infertility?

It can in some cases, particularly if both testicles are affected or inflammation is severe. Many men recover without lasting fertility problems, but follow-up may be worthwhile if you are trying to conceive.

What is the difference between orchitis and epididymitis?

Orchitis is inflammation of the testicle. Epididymitis is inflammation of the epididymis, the tube behind the testicle. Because the two structures are close together, both may be inflamed at the same time.

Does orchitis always cause swelling?

Swelling is common, but the degree varies. Some men notice mainly pain and tenderness early on, while others have obvious enlargement of the testicle or scrotum.

Can you have orchitis without fever?

Yes. Fever can occur, especially with infection, but not every case includes fever. Lack of fever does not rule out a significant testicular problem.

Is sex safe if you have orchitis?

It is usually best to avoid sex until you have been medically evaluated and, if an infection is present, until treatment is underway and your clinician says it is safe. If an STI is involved, partner management is important.

Do I need a semen analysis after orchitis?

Not everyone does. It may be reasonable if you had a severe episode, both testicles were affected, or you are actively trying for pregnancy and want to check sperm health after recovery.

Can orchitis come back?

It can, depending on the underlying cause. Recurrence may happen if an STI is not fully treated, a urinary problem persists, or the original diagnosis was incomplete.

References

Centers for Disease Control and Prevention (CDC). Sexually Transmitted Infections Treatment Guidelines.
Urology Care Foundation. Patient education resources on epididymitis and orchitis.
Merck Manual Professional Edition. Epididymitis and orchitis.
NHS. Orchitis and epididymitis patient guidance.
Mayo Clinic. Orchitis overview.
American Urological Association (AUA) educational materials and clinical resources related to acute scrotal conditions.
World Health Organization (WHO). Mumps and vaccine-preventable disease resources.