Lice do not cause disease, but because they are easily transferred from head to head they can create headaches for parents and children. (CBC)

They're common, contagious and dreaded by parents of school-aged children, but head lice are not a health hazard, the Canadian Pediatric Society said Friday.

Still, social myths persist about the little critters, which can lead to misdiagnosis and overreaction, the CPS said.

"Head lice are not a sign of poor hygiene. Parents should not panic," says Dr. Jane Finlay, a member of the CPS infectious diseases and immunization committee and co-author of a new CPS position statement published Friday in the journal Pediatrics & Child Health.

"They are not a medical threat. It's more of an inconvenience," Finlay said in a release.

Head lice can spread easily, especially when people are in close contact. But to confirm a case of infestation, live lice must be present in the hair or on the scalp.

"People think they see eggs or nits, but these are easily confused with dandruff or the outer shell of the hair or flakes of skin," she said.

The CPS recommends treating head lice with an approved topical insecticide such as pyrethrins, permethrin or lindane. Lindane should be used only as a second-line therapy because of its toxicity.

The treatment of choice depends in part on a child's age.

"Lindane must be used with caution," said Finlay. "It is not appropriate for children under two."

A non-insecticidal lotion called isopropryl myristate/cyclomethicone has also been approved for use in Canada, but should not be used on children under age four.

The CPS warns that alternative and homemade treatments — such as mayonnaise, petroleum jelly, olive oil, margarine, hair gel or wet combing — don't work.

Because nits don't survive long away from the scalp and cannot hatch eggs at room temperature, there is no need to disinfect a home or school because of head lice, said the organization.

Children with head lice should be treated and continue to attend school or child-care programs as usual.

In March, environmental activists urged parents to avoid lice shampoos containing lindane because of its adverse effects on humans and the water supply.