Summer Penile Syndrome

Life is full of hazards! Chance encounters with life’s hazards seem to increase in the Summer time (ex, Trampolines, Snakes, Lawn Mowers, Water, and Heat). It is good that continue to raise awareness of such hazards so we can prevent them! Certainly, the care of pediatric patients is known for its “Seasonality.” Now that the long days of summer (for us in the Northern Hemisphere) might be behind us, some of those hazards may also be receding, but injuries and illnesses don’t always listen to the school calendar! Today, let’s consider a condition that occurs in the summer and may cause itching like there are ants/squirrels in your pantsLion’s Mane Penis or Summer Penile Syndrome:

Summer Penile Syndrome: Basics

  • Acute hypersensitivity reaction (Shah, 2021)
  • Due to bites from chiggers or Trombiculidae mites (Schulert, 2014)
  • Can also be caused by poison ivy, oak and sumac (Shah, 2021)
  • Usually painless
  • Pruritus is the most common symptom (84%) followed by dysuria (33%) (Smith, 1998)

Summer Penile Syndrome: Presentation

  • Edema of the penile shaft just proximal to glans (Shah, 2021)
  • Clinical diagnosis
  • Some will have visible insect bite on penis
  • Gets name “lions mane” due to circumferential edema of distal penile shaft surrounding glans (Shah, 2021)
  • Need to differentiate from other penile conditions:

Summer Penile Syndrome: Uncommon Complications

Summer Penile Syndrome: Treatment

  • Treatment is largely supportive care (Shah, 2021, Schulert, 2014, Smith, 1998)
    • Cold compresses 
    • Oral antihistamines 
  • Topical corticosteroids only if difficulty voiding or weak urinary stream (Shah, 2021)
  • Educate patient (and parent) that symptoms can last for up to 2 weeks (Shah, 2021)

Summer Penile Syndrome: Prevention

  • Insect repellent (Schulert, 2014)
  • Protective clothing (Schulert, 2014)

Moral of the Morsel

  • Lion’s Mane can be scary! Penile swelling can be distressing for patients and parents alike!
  • Insects like dark places. Their bites can occur anywhere they hang out!
  • A swollen penis is not always paraphimosis! Summer Penile Syndrome consists of painless pruritus with circumferential edema of the distal penile shaft just proximal to the glans
  • Basics are the Best! Treatment is supportive.


  • Schulert GS, Gigante J. Summer penile syndrome: an acute hypersensitivity reaction. J Emerg Med. 2014 Jan;46(1):e21-2. doi: 10.1016/j.jemermed.2013.08.081. Epub 2013 Nov 5. PMID: 24199728.
  • Shah A, Sobolewski B, Mittiga MR. Summer Penile Syndrome. In: Knoop KJ, Stack LB, Storrow AB, Thurman R. eds. The Atlas of Emergency Medicine, 5e. McGraw Hill; 2021. Accessed September 06, 2023.
  • Smith GA, Sharma V, Knapp JF, Shields BJ. The summer penile syndrome: seasonal acute hypersensitivity reaction caused by chigger bites on the penis. Pediatr Emerg Care. 1998 Apr;14(2):116-8. PMID: 9583392.
Ali Rosser
Ali Rosser
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