Pubic Lice (Crabs): Symptoms & Signs

Medically Reviewed on 9/22/2020

Pubic lice are parasitic insects that infest the genital or pubic areas of humans. The lice have also been referred to as crab lice or crabs.

Signs and symptoms of pubic lice include

  • itching in the affected areas (especially at night),
  • inflammation and irritation caused by scratching, and
  • blue spots or small spots of blood on your skin, such as on your thighs or lower abdomen (caused by lice bites).

Visible crawling lice or nits (lice eggs) may also be apparent.

Causes of a pubic lice infestation

The infestation typically spreads among humans by sexual contact and are considered to be a sexually transmitted disease (STD). They may also spread from close personal contact or contact with articles such as clothing, bed linens, or towels that have been used by an affected person.

Other pubic lice (crabs) symptoms and signs

  • Blue Spots or Small Spots of Blood on Your Skin, Such as on Your Thighs or Lower Abdomen (Caused by Lice Bites)
  • Inflammation and Irritation Caused by Scratching
  • Itching in the Affected Areas (Especially at Night)


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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.