Lice Advice

Information and Treatment About Head Lice

The Louisville Metro Department of Public Health and Wellness does not support a "no nit" policy. The two links below provide more information:
Harvard School of Public Health
CDC Parsitic Disease Information

How do they spread?

  • Direct contact: Head-to-head contact
  • Indirect contact: Sharing personal items such as combs, brushes, scarves, hats and coats, "dress-up" clothes, head phones, stuffed animals, and shared surfaces, i.e. sleeping mats.

Head lice are not spread by pets. They do not jump or fly. (They need fibers to grasp onto, therefore, smooth surfaces on items such as desks, non-upholstered furniture, non-carpeted floors and tables will not transmit head lice.)

What to do when an active case of head lice is found?

Treatment Procedure

1. Wash clothes, bed linens, and towels in hot water, (130 degrees) then dry on the hot cycle for at least 20 minutes. Items such as stuffed animals, head phones and hats that are not machine washable must be dry-cleaned or stored at room temperature in a tightly sealed plastic bag for at least two weeks.

2. Vacuum all rugs, carpets, upholstery, headrest, carseats, mattresses and pillows. Immediately throw away the vacuum cleaner bag.

3. Disinfect combs, brushes, sports helmets and other objects that come in contact with the head by soaking in medicated shampoo or disinfectant for 30 minutes.

Disinfectant: 1 quart of water mixed with 1 1/2 teaspoon of Lysol.

General Information:

NITS: (Lifespan 7-10 days)

Nits are laid at the junction of the hair shaft and the scalp, and are firmly attached to the hair shaft by a cement-like substance. They hatch in 7-10 days. Hair grows about one fourth of an inch a week, and therefore, any nits found further than one-half (1/2) inch from the scalp have either hatched (hatching pushes them down the hair shaft), or are infertile. Nits seen within one-half(1/2) inch of the scalp are indicative of an active infestation. However, the presence of any lice or nits on a person with no documented treatment should be considered an active infestation. Nits can survive off the host's head and hatch, but they need a blood meal quickly. Nits die quickly at temperatures below 75 degrees or above 98 degrees, but if kept in a constant temperature, they can hatch off the body in 7-10 days. Nits can be light, tan or dark, depending on the color of the host's hair.

NYMPHS: (Lifespan 8-9 days)

When the eggs hatch, the louse is then in nymph form. They are about the the size of a piece of pepper. It takes them 8-9 days to develop into adulthood and sexual maturity.

ADULTS: (Lifespan 30 days)

Mating occurs shortly after adulthood and continues until death. A female adult louse lays 2-5 nits a day during her thirty day lifespan. The adult head louse is the size of a small ant, it varies in color depending on the host's hair color. The louse holds onto hairs with hook-like claws, located at the ends of its six legs. To feed, the louse stabs an opening through the skin and sucks blood into its digestive tract. They feed primarily at night and are very sensitive to light. Louse bites cause tiny red spots on the scalp and cause intense itching. Lice are found primarily behind the ears and at the nape of the neck although they can be anywhere on the scalp. Lice can only live 24-48 hours off the host, they need a blood meal every 3-6 hours.

Common Treatment Problems:

1. Not following package directions exactly. Product may not be effective if directions are not precisely followed.

2. Retreating the head because nits are still present after initial treatment. There is no head lice medication that gets rid of the nits. They must be removed by nit comb and fingernails immediately after the treatment. Retreat only if live bugs are seen in seven days, or if the product instructions recommend it.

3. Treating the head repeatedly to prevent head lice. Nix is the only product, when used correctly, that will protect from reinfestation for up to two(2) weeks. When there is not an active case of lice, repeated treatments can lead to scalp irritation, systemic toxicity (with some products), and possible drug resistance.

4. Live bugs present after treatment with Nix. Nix will kill about 70% of lice immediately. The other 30% become sterile and die within a few hours. Therefore it is possible to see live lice after nix treatment. If you still find lice after seven (7) days, retreat child.

5. Child continues to scratch head after treatment and is retreated without evidence of lice or nits. All head lice medications cause drying and irritation of the scalp, which can lead to itching and flaking of the scalp.

6. Misidentifying head lice. Hairspray and dry scalp can be mistaken for nits. Dry scalp will move when touched. Recommend washing out hairspray and reinspecting head.

Comparison of Head Lice Treatments

Brand NIX RID/A-200R & C/Pronto
Active Ingredient Permethrin Pyrethrins
Availability Over the Counter Over the Counter
Reinfestation Protection 14 days*
Only 1 application needed for maximun efficacy Yes No-Retreat in 7-10 days
Product Application Apply to clean wet hair. Wash hair in sink not tub or shower. Apply to clean wet hair. Wash hair in sink not tub or shower.
Warning: The use of vinegar or enzyme rinse can ,make the treatment ineffective if used after treatment. Yes No
Do Not use these products if: Allergic to Pyrethrins or Mums. Allergic to the drug or ragweed or if scalp is raw or inflamed.
Side Effects Skin: Itching, burning, tingling, numbness, mild redness. Scalp: Discomfort or rash Discourage
repeated use which can lead to skin irritation, and possible poisoning.
*The hair is protected for fourteen (14) days if you do not shampoo for two days after treatment, then shampoo as infrequently as possible for the next two weeks with mild shampoo.

Note: Due to its toxicity Lindane or Kwell is not recommended for the treatment of head lice.

Common Questions About Head Lice And Treatment

1. Do head lice transmit disease?

2. Will a hair permanent get rid of head lice? No

3. Do commercial hair dryers get hot enough to kill lice?

No. If temperatures hot enough to kill lice were produced, extreme discomfort or burns would result.

4. Will hairspray prevent you from getting head lice? Will hairdressing (Vaseline, baby oil, etc.) prevent head lice and/or nit attachment?

No to both.

5. Do vinegar rinses control head lice?

6.Do home remedies (i.e. bleach kerosene, coal oil) work just as well as head lice treatment.

No. These products are not safe to use and not approved for head lice treatment.

7. Should hair be kept short to prevent getting head lice?

No. Studies have indicated that long hair is not more likely to be infested than short hair.

8. Should hair be cut to get rid of head lice?

No. Most eggs are within 1/2 inch of the scalp.

9. Is head lice infestation related to uncleanliness?

No. Head lice can occur at all social and economic levels.

10. Can lice hop and jump?

No. They have claws to cling to the hairshaft.

11. Should a home or school be sprayed, dusted or otherwise treated with insecticides when a person has head lice?

No. Lice do not hide in wall crevices and floor cracks like cock roaches or other household pets.
12. Can pets give head lice to humans?
13. Can I use a pet shampoo for head lice treatment?

No to both.

Please call (502) 574-5243 if you need additional information

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