Lice

Symptoms

Itching, the most common symptom of all types of lice infestation, is caused by an allergic reaction. Lice bite the skin to feed on a person's blood. The saliva from these bites causes the allergic reaction and itching.

Itching may not occur right away, depending on a person's sensitivity and history of lice infestation. The first time a person is infested with lice, it may take several weeks or months for itching to develop or to be noticed. In a repeat case of lice, a person may begin to itch within 2 days of infestation because the immune system reacts more quickly when exposure has occurred previously.

Some people become very sensitive to lice bites and have unbearable itching. Others build up tolerance to the bites and have little or no itching, even with repeated infestations.

In addition to itching, symptoms of lice infestation vary depending on which type of lice is present.

Head lice

Head lice and their eggs (nits) can be seen on hair, the nape of the neck, and behind the ears. They can vary in colour from white to brown to dark grey. The eggs are tiny round or oval shapes that are tightly attached to the hair near the scalp and do not slide up and down on the hair.

Frequent scratching may cause broken skin or sores to form on the scalp. The damaged skin may weep clear fluid or crust over, and it may become infected. In response to infection, the lymph nodes behind the ears and in the neck may become tender and swollen.

Pubic lice

A pubic lice infestation may cause itching around the genitals as well as the anus, armpits, eyelashes, and other body areas with hair. Pubic lice bites may cause small, flat, blue-grey, bruise-like marks (maculae cerulea) on the torso, thighs, or upper arms. The marks may last for several months, even after all lice have been killed. Pubic lice, like head lice, can be seen on shafts of hair.

Pubic lice that infest the eyelashes and eyelids may cause irritation and crusting in those areas. The lice may be visible near the base of eyelashes.

Up to one-third of people who have pubic lice also have some other sexually transmitted infection (STI).¹Symptoms of STIs can include itching, tingling, burning, or pain of the genitals. STIs are also called sexually transmitted diseases (STDs). For more information about STIs, see the topic Exposure to Sexually Transmitted Infections.

Body lice

Itchy sores from body lice usually develop in the armpits, around the waist, and along the trunk where seams of clothes press against the skin. The lice and eggs are generally not seen on the skin but may be found in the seams of the person's clothing.

Other conditions, such as dandruff or scabies, can cause symptoms similar to those of a lice infestation.

Go to previous section	Go to top of page	Go to next section
Author:	Debby Golonka, MPH Carrie Henley	Last Updated: February 13, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine Michael J. Sexton, MD - Pediatrics Thomas Emmett Francoeur, MDCM, CSPQ, FRCPC - Pediatrics
© 1995-2008 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.