Layer 1

How to recognise and treat headlice


Pharmacy teams play an important role in offering advice on headlice. Do you know how to recognise an infestation and advise on management options?

From this sponsored pharmacy CPD module on headlice you will learn about:

  • How common headlice are and who is affected
  • How to recognise a headlice infestation
  • The management options for this condition
  • Advice and information to give about treatment and what to do about recurrence

Download a printable PDF of this module – including the five-minute test – here.

Perrigo has paid for this piece and has been involved in its creation and editing

Recent guidance from NHS England on items that should not routinely be prescribed in primary care,(1) and conditions for which over-the-counter items should not routinely be prescribed (including headlice),(2) has placed more emphasis on self-care for patients.

Pharmacies offer a key source of advice and information to ensure that patients are supported to treat conditions such as headlice appropriately.

Headlice can move from one scalp to another (their primary means of transmission) in around 30 seconds when the heads of infested individuals are in close proximity. They can also be spread by people sharing personal items such as hats, combs or pillows,(3) although this only happens rarely.(4)

Who is affected by headlice?

Headlice are the most common ectoparasitic disease in the world.(5)

They can affect anyone, but infestation is more common in:(6)

  • children between the ages of 4 and 11 years (the peak is 7-8 years)
  • girls than boys
  • the start of the school year
  • children with long hair.

There is not much data on prevalence of headlice infestations in the UK; studies suggest that 4-22% of children might be infested.(6) About a dozen lice will typically be found on a person’s head, but in a small minority of cases (about 5%) more than 100 lice can be found.

What are headlice?

Also known by the Latin name Pediculus humanus capitis, headlice infest the hairs on human heads and feed on human blood.(6) They need to feed several times a day and the characteristic itch people with headlice experience is a result of the bites, saliva and faeces from the lice. Someone infested for the first time may not scratch for 4-6 weeks after the infestation begins, because it takes time for skin sensitisation to develop.(4) Without a supply of blood from a human scalp, headlice will die within one or two days.(3)

Louse eggs (known as ova) are attached to hair near the surface of the scalp with a glue-like substance. They are oval and translucent – sometimes mistaken for dandruff – and take about 7-10 days to hatch as nymphs. The empty shells left after the lice have hatched are known as nits. Adult headlice are up to 3mm long – a similar size to a sesame seed. They are a tan to grey colour, with six legs and hook-like claws that they use to hold onto hair. An adult louse can live for 30-40 days, during which time a female can lay 50-150 eggs.(6)

Headlice myths dispelled

Parents or carers may present in the pharmacy with a number of concerns about headlice. You must ensure that you can arm them with the right information to suitably treat the infestation. To do this it may be necessary to dispel some common myths.  



Myth Fact

Headlice can fly and jump between heads

Headlice are wingless insects that cannot fly, jump or swim. They are spread mainly by head-to-head contact.

Headlice prefer unclean hair

Headlice are not fussy; they can be found on clean or dirty hair.

Headlice are spread by pets

Human lice are not found on pets and therefore cannot be transmitted by them.(7)

Headlice pose a danger to health

If headlice are not in contact with a human scalp they die quickly.(8)

Affected children should stay away from school

Headlice do not mean children have to stay away from school, because it's unlikely to help prevent their spread.

Headlice lifecycle

  1. Female lays eggs (nits) at the base of the hair shaft nearest the scalp.
  2. Nymph (immature louse) hatches from egg 7-10 days after being laid and feeds on blood from host.
  3. Nymph develops into an adult, after moulting three times, 9-12 days after hatching from egg.
  4. Adult louse continues to feed several times daily, then mates and reproduces, with a female laying as many as 8-10 eggs per day.
  5. Mature louse dies after approximately 30 days.
What are the consequences of not treating headlice?

If left untreated, a headlice infestation can continue for a long time and may lead to complications such as:(6)

  • pruritic rash on the back of the neck and behind the ears
  • anxiety, distress and stigma.

Rarely there may be:

  • excoriation and skin infection
  • loss of sleep, because of the urge to scratch all the time.
How is headlice diagnosed?

Finding a live louse is not easy, because they avoid light and crawl quickly. Eggs may be easier to spot at the nape of the neck or behind the ears, about 1mm from the scalp. However, they may be mistaken for dandruff, hair casts or other debris, all of which are much easier to remove than a louse or its egg.(4,6) Nevertheless, the gold standard for diagnosis is finding a live louse on the head.(4) The best way to confirm a headlice infestation is with detection combing, which in one study conducted in 461 Turkish school children was found to be almost four times more effective than visual inspection for detecting live headlice.(5)

Detection combing can be done on wet or dry hair with a fine-toothed comb, although wet combing is believed to be more accurate because the lice stay still. While it is not essential to use wet combing, it may be the better option for people with very thick hair as it can stop the build up of static, which may result in lice being ejected from the comb as it is taken out of the hair, raising the risk of transmission.

A detection comb differs from the combs used to remove headlice: it is usually made of plastic and the teeth should ideally be 0.2-0.3mm apart, so that they trap headlice and nymphs.

How to detect lice by wet combing

Depending on hair length and type, wet detection combing takes about 10-15 minutes (in comparison, dry detection takes around 3-5 minutes).(6)


  • Wash the hair with ordinary shampoo
  • Apply enough hair conditioner to help straighten and untangle the hair using a wide-toothed comb
  • When the wide-toothed comb can be moved through the hair without dragging, use a detection comb as follows:
  • Comb from the hair roots through to the tips, with the comb touching the scalp as much as possible
  • Remove any lice found on the comb after each stroke by wiping or rinsing the comb (this needs good lighting and possibly a magnifying glass)
  • Work in sections so that all the hair is combed through
  • Rinse the conditioner out
  • Comb a second time to check for lice missed the first time
  • Finally, dry the hair.

How to detect headlice by dry combing

Once hair is tangle-free and a normal comb passes through it easily(6):

  • comb from the crown to the tips of the hairs; work around the head in sections until all the hair has been combed through
  • comb each section of hair 3-4 times
  • look for lice as the hair is combed, using a thumb to trap lice against the face of the comb to stop them being ejected by static electricity.
How to confirm an infestation

An infestation can be confirmed only if a live headlouse is found. Itching, eggs or nits do not confirm headlice are present. It is important to check all close contacts, family members, people living in the same house etc, as they may be a source of reinfestation.

How should a headlice infestation be managed?

Treatment should not be started without evidence of an infestation (ie detection of at least one live louse) and should be guided by local policy.

Treatment products

Generally, treatments that work either physically or chemically on headlice are used. Physical treatments tend to be recommended as a first-line. Malathion may be used as an alternative, but resistance has been reported.(7)

Treatments that work physically on headlice contain silicone compounds or fatty ester as the active ingredient.(6) They work by covering the spiracles (openings on the abdomen that allow air to enter the tracheal system used for breathing) thus preventing lice from excreting water. This causes physiological stress that kills lice due to prolonged immobilisation or sometimes disruption of internal organs.(11)

Wet combing

An alternative approach is wet combing. This involves systematic hair combing with a louse comb to remove headlice using hair conditioner or vegetable oil, for example, rather than a physical insecticide. The method is very similar to the wet comb detection technique outlined above and it can be effective if done properly. The important thing is to be thorough and repeat the combing at least once initially and then every 3-4 days (see table below). Treatment is deemed successful if no lice are found after the last detection combing session.

For pregnant or breastfeeding women, young children aged six months to two years, and people with asthma or eczema, wet combing or dimeticone 4% lotion are preferred.(6)

Headlice combs are either metal or plastic and the choice is largely down to personal preference. There is some evidence that a metal comb might be more effective than a plastic one.(12) However, Nice (National Institute for health and Care Excellence) Clinical Knowledge Summaries comment that hair may be pulled out by metal combs.(6)

Headlice treatments: application and advice
Method Active Ingrediants Application time/frequency Notes

Physical (insecticides and noninsecticides)

Isopropyl myristate


Isopropyl alcohol


Formulations require between five minutes and eight hours before combing or washing out

Many products should be applied to dry hair

Applied twice, at least seven days apart

Detection combing

UKMi recommends: two or three days after the second treatment and on day nine or 10

CHC recommends: days five, nine and either day 12 or 13 after the first application

Chemical (insecticides)



Formulations require between 10 minutes and eight hours (permethrin) or 12 hours (malathion) overnight

Repeat treatment after seven days

Wet combing

Hair conditioner

Vegetable oil (BNF)

Four sessions over two weeks (on days one, five, nine and 13)

Detection combing

CHC recommends: days five, nine, 12 or 13, and 17 after the first application

BNF = British National Formulary; CHC = Community Hygiene Concern; UKMi = UK Medicines Information(10)

* Not generally recommended by Nice due to resistance

Alternative treatments

Patients or carers who are concerned about headlice infestation may consider alternative or complementary treatment options. It is important you are aware of these so that you can provide them with accurate advice. An example includes battery-powered headlice combs.

These combs, designed to be used for detecting and killing headlice, are available, but no formal trials of their efficacy have been published.(4) They can only be used on dry hair, and are not suitable for children under three years old or people with epilepsy, heart disease or a pacemaker.(13) If you stock these items in your pharmacy you should ensure your team understand how they are used and their limitations.

Practical tips for parents and carers

Although infestation is the correct term for describing a person affected by headlice, some authorities feel it makes sense to talk about an infection when advising parents. This may help reduce feelings of guilt and put the condition in the same category as other minor ailments, such as colds and sore throats.(7)

You should also remind parents/carers that treatment should not be started unless a live louse has been found on the head of the person in question.

When advising on headlice and its treatment remember to:

  • explain that it is important to read the product instructions to ensure it is used safely and correctly; for example, many products should be applied to dry hair as an initial step(14)
  • advise parents/carers that all affected family members should be treated on the same day to avoid reinfection
  • warn parents and carers about the need to avoid open flames, because of the risk of fire with some products (see individual product instructions for details).(15)

For treatment products (see table above) explain that:

  • treatment should be applied to all areas of the scalp and from the roots to the tips of all hair
  • the product should be left on for the time recommended by the manufacturer, then washed off
  • it is generally recommended that treatment products are applied twice, at least seven days apart, to treat lice hatching from eggs before they lay more eggs. Some experts suggest three applications may be needed for eradication
  • inappropriate use can lead to treatment failure and may increase the risk of resistant lice
  • hair should be kept away from naked flames, cigarettes etc, during treatment with dimeticone containing products (though not flammable, dimeticone is not water-based and will not prevent hair from burning)
  • care should be taken if the product is spilt, as it may cause a slip hazard
  • after treatment, detection combing should be done to check that the treatment was successful (see table above). Treatment is deemed successful if no lice are found.

For wet combing explain that:

  • four applications over two weeks are recommended
  • short hair takes about 10 minutes; long, frizzy or curly hair takes around 20-30 minutes
  • comb hair twice during each treatment
  • a fifth detection combing session should be done on day 17. Treatment is considered successful if no lice are found.

What to do about reinfestation

The presence of louse eggs alone (hatched or unhatched) and/or itching does not indicate treatment failure. However, in the event of a treatment not working and reinfestation occurring it is important to check that initial treatment was carried out correctly.

For example, whether enough product has been used (an adult will need 50-100ml of lotion or creme rinse per application)(6,16) or if it has been applied correctly and left on (or combing continued) for long enough and repeated the correct number of times where appropriate. Potential sources of reinfestation should be sought by assessing household members, close family and close friends (both adults and children).

Treatment should be repeated, including treating all affected household members at the same time.

Where else can I find information about headlice?

There are several sources you can refer parents or carers to for further information:

Headlice CPD – planned learning

What are you planning to learn?

I want to learn more about headlice, including how common they are, who is most likely to be affected and how to detect a headlice infestation. I want to learn about the different headlice treatments available and how they should be used. I also want to improve my knowledge of the advice and information that pharmacists can give to patients and what to do about recurrence.

This learning will help me to improve my knowledge of the latest recommendations for the detection and treatment of headlice and to be able to provide better, more effective advice to the patients I serve in my pharmacy.

How are you planning to learn it?

    • I plan to read more about headlice on the Patient website.
    • I plan to read the information about mistaken advice on the Community Hygiene Concern website.
    • I plan to find out more about the OTC products available for the treatment of headlice from the C+D OTC Guide to Medicines and Diagnostics.

    Give an example of how this learning has benefited the people using your services

    A mother came into the pharmacy asking for advice about treating recurring headlice infestations. She had three young children with headlice that never seemed to go away despite treatment. She asked for a strong insecticide and was considering treating everyone in the family. I was able to dispel some headlice myths and reinforce the latest treatment guidelines. I explained why past treatments may have failed and suggested wet combing for detection. I advised only treating if live lice were found, to prevent unnecessary treatment on the basis of seeing empty nit cases. I also signposted her to reliable sources of information and advice.


    1. NHS Clinical Commissioners. Items which should not routinely be prescribed in primary care: Guidance for CCGs. London: NHS England, 2017.
    2. NHS Clinical Commissioners. Conditions for which over the counter items should not routinely be prescribed in primary care: Guidance for CCGs. London: NHS England, 2018.
    3. British Association of Dermatologists. Patient Information Leaflet (2017) Head lice.
    4. Frankowski BL, Bocchini JA. Clinical Report – Headlice. Pediatrics 2010;126:392–403.
    5. Balcioglu C, Burgess IF, Limoncu ME, et al. Plastic detection comb better than visual screening for diagnosis of head louse infestation. Epidemiol Infect. 2008;136(10):1425–1431.
    6. National Institute for Health and Care Excellence (Nice) Clinical Knowledge Summaries (CKS) (2016) Head lice.
    7. UK Medicines Information. Cymru Wales. Head lice. Questions and answers for healthcare professionals. Cardiff: UKMi, 2014.
    8. Nash B. Extracts from Best Practice: Treating head lice. BMJ 2003;326:1256–8.
    9. Centers for Disease Control and Prevention. Parasites: Head lice – biology
    10. BNF (2019) Permethrin.
    11. Burgess IF. The mode of action of dimeticone 4% lotion against head lice, Pediculus capitis. BMC Pharmacol 2009;9:3.
    12. Speare R, Canyon DV, Cahill C, et al. Comparative efficacy of two nit combs in removing head lice (Pediculus humanus var. capitis) and their eggs. Int J Dermatol 2007;46(12):1275–8.
    13. Electronic Headlice Comb 3 Years Plus.
    14. Chemist+Druggist. Guide to OTC Medicines and Diagnostics. December 2019. London: Informa Healthcare, 2019.
    15. Drug Safety Update. Head lice eradication products: risk of serious burns if treated hair is exposed to open flames or other sources of ignition, eg, cigarettes.
    16. British National Formulary. Parasiticidal preparations for the skin. Head lice.

    Job of the week

    Chief Officer
    East Midlands
    Circa £25,000-£30,000 PA based on a 22.5 hour week