What are head lice?

Head Lice are on the riseAt any given time in the UK, over 2 million children under the age of 15 are suffering from an infestation of head lice 7,8.

Head Lice
are insects that live in human hair and feed on human blood.

male and a female louse

  • They are tiny - about 2.0 to 3.5 mm long - and brownish in colour.

  • You are most likely to find them behind the ears, around the nape of the neck and at
    the temples.

  • They cannot jump or fly, but they have strong claws. If two children's heads are very close
    together, the lice can move from one to the other. An adult louse can cover 23cm
    in a minute.

  • A louse lives for about 50 days (seven weeks).

  • To suck blood, lice puncture the skin. This can cause severe itching. Continued scratching can lead to inflammation, as can allergic reactions to louse spittle and droppings.


The eggs or empty egg cases of head lice are called nits .

  • Eggs (nits) are about the size of a grain of sand, and are white or brownish in colour
  • Eggs (nits) stick very firmly to the hair shaft and can be very difficult to remove.
Lice in Hair Magnified eggs on hair





Newly hatched lice are called nymphs . Female lice start laying eggs when they are about three weeks old.

Head lice statistics
  • A third of all UK schoolchildren under 16 (4.06 million) were treated for head lice infestation an average of 3.6 times over the last year.
  • The figure rises to 48% for children of primary school age (4 to 11).
  • 16% (4 million) of British parents say they have caught lice from their own children.
  • Only 39% of parents report treatment success in eradicating head lice.
  • NYDA® is scientifically proven to kill head lice in one minute and their eggs in eight hours.
  • NYDA® is 95% effective after one application. This means that 95% of people using NYDA® will experience treatment success 13.

For references indicated with superscript, digits or asterisks, please click here:  References

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