Body lice

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at May 20, 2016
StartDiseasesBody lice

Tiny insects similar in size to a sesame seed, body lice inhabit clothing and bedding and feed on human blood. Because body lice need nourishment several times per day, they must travel onto human skin where they bite to access blood. These bites and allergic reactions to body lice's saliva cause severe itching for the host person, sometimes causing secondary infections. After feeding, the insects return to textiles they inhabit, laying eggs and depositing waste. Body lice are transmitted from human to human, within unhygienic living conditions or through wearing dirty clothing. Body lice are also known as Pediculus humanus corporis.


Definition & Facts

Only measuring 2.3 to 3.6 millimeters in length at maturity, body lice thrive in unhygienic conditions. They are known to spread disease and are transmitted from person to person through close physical contact or sharing of clothing or bedding. Body lice bites are usually worst where clothing is closest to skin. 

Although similar to head lice, body lice are slightly larger and have different living habits. Head lice live in their host human's hair, feeding on the scalp. Body lice travel to and from their host person, living and laying eggs, known as nits, in clothing and bedding. 

Infestations, also known as pediculosis, are common in conditions of crowded living. Homeless shelters, refugee encampments, prisons and other environments of close inhabitation commonly experience such lice infestations. Household pets do not transmit lice to humans. Body lice can be effectively treated through improvement of living conditions, better personal hygiene, wearing only laundered clothing, and regular change of bed linens. 

Symptoms & Complaints

First symptoms experienced when body lice are present include intense itching and telltale signs of the presence of lice, such as small spots of blood, red bumps or crusting on the skin where bites have occurred. If infestations are allowed to continue for very long, skin around the waist and groin can become thickened and discolored. Skin often becomes reddened and raw from excessive scratching of body lice bites.

Itching from bites of body lice is due to an allergic reaction to the insects' saliva. This itching is usually worst in places where clothing is in most frequent contact with the body, such as:

There are more serious complications that can occur from body lice infestations. These include:

  • Secondary infections caused from irritation of the bite or scratching
  • Thickening or discoloration of skin where body lice have been allowed to remain for a long period of time, such as around the waist, groin and thighs
  • Diseases commonly spread by body lice, such as typhus, trench fever, and relapsing fever


Body lice infestations are generated through person-to-person interactions, by wearing clothing infested with lice, or by being in contact with bedding infested by the insects. These lice live in creases, folds and seams of fabric, feeding on human blood and laying eggs on skin and textiles where they live. Body lice have a life cycle of up to one month in clothing or other fabrics, but die within five to seven days if they lose access to a human host. 

The most frequent causes of body lice infestations are poor hygiene and overcrowded living arrangements. Regular bathing and laundering of clothing and other fabrics are important for prevention of lice infestations. Places where people live in the aftermath of natural disasters, when homeless, during war, or as part of imprisonment are often sites of lice infestation due to the crowding and inaccessibility of hygienic resources in these places. 

Diagnosis & Tests

Diagnosing a body lice infestation is fairly simple. The healthcare provider inspects the patient's skin and clothing to find signs of the insect's presence. When lice are present, there are physical indications of lice activity on the patient's skin. These include:

  • Adult lice, crawling insects with six legs, tan to gray color and size similar to a sesame seed
  • Nits, the eggs of lice often found in clothing, around the host's waist and in their armpits
  • Bite marks with a small amount of blood or redness surrounding the bite
  • Redness and scratch marks in areas around bites, due to the extreme itchiness these bites cause
  • Discoloration or thickening of areas of skin around the waist, groin or thighs, where lice have long been active

Treatment & Therapy

Treatment of body lice can be quite inexpensive and simple. The primary form of treatment is laundering of clothing, towels, sheets and other household linens in hot water and soap, as well as bathing of the patient in a hot bath or shower. Steaming, ironing, vacuuming and dry cleaning are effective for fabrics that cannot be laundered, such as suits, car seats or upholstery.

Over-the-counter shampoos and lotions are often used to quickly eradicate infestations on humans. Prescription variations called pediculicides are also available through a doctor. However, these products can be toxic to humans, so use must be weighed according to need. For severe cases of body lice infestation, a doctor may prescribe an oral medication.

Items that cannot be effectively cleared of infestations just through cleaning, such as mattresses and furniture cushions, should be surface cleaned using a vacuum, steamer and/or lice treatment solutions. These items should then be completely avoided by humans for a minimum of two weeks. This will allow enough time for the remaining body lice to die. The materials can then be cleaned again to remove the dead body lice, residue, waste and nits.

Prevention & Prophylaxis

Preventing body lice infestation comes down to avoiding physical contact with others who have body lice, not sharing clothing or other textiles with these people, and keeping oneself and living spaces clean. Regular bathing and changing of clothing at least once per week is crucial for prevention of a personal infestation. Once an infestation has been treated, this cleanliness must continue to prevent re-infestation.

Doctors recommend the following actions to prevent and control body lice:

  • Regular bathing
  • Wearing only properly laundered clothing
  • Machine washing and drying of clothing using the highest heat seatings according to specific fabric types
  • Frequent changing of bed linens and towels, at least once weekly
  • Avoidance of sharing beds, bedding, clothing, towels or other textiles with others
  • Periodic fumigation of living spaces for control and prevent of body lice and other insects