Summer Penile Syndrome

Summer penile syndrome is a skin condition that causes swelling and an itchy, discolored rash on your penis during the warm weather months. It mostly affects boys. But it can also affect adults.

Chigger bites cause most cases of summer penile syndrome. Chiggers (Trombicula) are a type of tiny arachnid — from the same family as spiders and ticks. They’re most active in the summer and early fall, especially in the warmer, humid southern United States. They prefer wooded, grassy and moist outdoor areas.

Other names for summer penile syndrome include:

• Summer penis syndrome
• Lion’s mane penis
• Seasonal acute hypersensitivity of the penis
• Trombiculosis or trombiculiasis of the penis

Symptoms of summer penile syndrome

Summer penile syndrome symptoms include:

• Itchy skin
• Discoloration (red, purple, black or brown)
• Swelling in the shaft of your penis

If you still have your foreskin, it’s also possible for it to swell and get stuck behind the head of your penis (paraphimosis).

Causes

The most common cause of summer penile syndrome is bites from the baby form of chiggers (larvae). Chigger larvae attach to your clothes when you walk through an infested area. Then, they work their way to an exposed area of your skin. They also attach to pet fur. You can pick up the mites from touching an animal that has them.

Chigger larvae don’t bite or burrow into your skin. They use their tiny, sharp claws to dig a small hole (stylostome) into your skin and inject spit (saliva). Enzymes in their spit break down skin cells. The larvae feed on the broken-down skin cells, which helps them grow into adult chiggers. Itchy bumps form around the small holes they dig in your skin. The itching is an allergic reaction to the enzymes in the larvae spit.

Though not as common, summer penile syndrome can also develop after exposure to poisonous plants, like:

• Poison ivy
• Poison oak
• Poison sumac

An oily sap (urushiol) from these plants causes a type of allergic contact dermatitis. Summer penile syndrome may develop if the oil gets on your genitals. This may happen from direct contact between your genitals and the plant. But it can also happen if you get the oil on your hands and then touch your genitals, like when using the bathroom.

Complications

It’s rare but possible to develop a bacterial skin infection like impetigo or cellulitis from a bug bite. Bacteria can enter your broken-down or damaged skin. Scratching can break open your skin more, allowing infection-causing bacteria to enter.

How doctors diagnose summer penile syndrome

A healthcare provider will:

• Review your medical history
• Ask about the symptoms
• Perform a physical exam

If they suspect summer penile syndrome, they’ll ask about any recent outdoor activities or plant exposures. They may also check your genital area for small bumps (nodules) that look like bug bites. Rarely, a mite may still be visible on or near the affected skin.

How is summer penile syndrome treated?

Your healthcare provider may recommend:

• Over-the-counter oral antihistamines to ease an allergic reaction
• Hydrocortisone cream that you rub on the affected areas
• Oral corticosteroids to treat severe symptoms
• Topical antibiotics for bacterial skin infections

You can also help calm an itchy rash by:

• Applying a cold compress or an ice pack wrapped in a towel
• Taking a cold bath

Recovery time

In most people, penile swelling improves within a few days. But it may take up to two weeks for the itching to go away.

When should I see my healthcare provider?

Call your healthcare provider if you have:

• Swelling on your penis or other areas around your genitals
• Pain when you pee or difficulty peeing
• Signs of infection, including discolored (red, purple, brown or black) streaks on your skin, yellow discharge or swollen lymph nodes

During your appointment, you may want to ask:

• What caused summer penile syndrome?
• What treatment do you recommend?
• How can I prevent it in the future?
• Are there any long-term complications I need to know about?

What can I expect if I have summer penile syndrome?

Summer penile syndrome feels uncomfortable, and a swollen penis can look alarming. But the outlook is good. Summer penile syndrome usually goes away with minor treatment. It rarely causes long-term problems.

Can it be prevented?

The following steps can protect you or your child from chigger bites and poisonous plants:

• Apply an EPA-approved insect repellant that contains DEET.
• Wear long sleeves and long pants in grassy or wooded areas.
• Tuck your pants into your socks or boots to minimize skin exposure.
• Treat your clothing and shoes with the insecticide permethrin.
• Bathe or shower with warm, soapy water as soon as you come indoors.
• Wash outdoor clothes in hot water and laundry detergent.
• When camping, avoid using plants or leaves as a substitute for paper products, like towels or toilet paper.