Piperonyl butoxide is a chemical that stops the breakdown of pyrethrins, an insecticide chemical.

Pronto Lice Kill System (for the skin) is a combination medicine used to treat lice.

Pronto Lice Kill System may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Lice infestations are highly contagious. All household members may need to be treated for lice. Lice can be spread from person to person by sharing a hairbrush, a comb, hats, or headbands. It can also be spread through head-to-head contact.

Apply the shampoo to dry hair. Shake well before use. Apply to all areas of the scalp, including behind the ears and neck. Treat hair from the roots to the ends and leave the shampoo in the hair for no longer than 10 minutes, then rinse thoroughly with warm water. The shampoo should be used again in 7 to 10 days to kill any newly hatched lice.

Keep your eyes tightly closed while using this medicine in your hair. You may use a washcloth or towel to protect your eyes while applying the medication to your head. Do not apply to your eyebrows or eyelashes. Call your doctor if these areas become infected with lice.

You will need to remove any eggs (nits) from the hair shafts with a special comb. Some lice products come provided with a nit comb. If you do not have such a comb, ask your pharmacist where you can get one. Nits may not be removed effectively with a regular fine-tooth comb.

Use this medication for the full prescribed length of time. Your symptoms may improve before the lice infestation is completely cleared. Call your doctor if your condition does not improve, or if your symptoms get worse while using this medication.

To prevent reinfection with lice, wash all clothing, hats, bed linens, stuffed toys, hair brushes, and combs in hot water with a strong cleanser to remove any mites or eggs. You may need to use a special lice control spray to treat furniture, mattresses, sports helmets, headphones, and other non-washable items. Ask your doctor or pharmacist about disinfecting your home.

Store the medicine at room temperature away from moisture and heat.

You should not use Pronto Lice Kill System if you are allergic to it, or if you have an allergy to chrysanthemums or ragweed.

FDA pregnancy category C. It is not known whether Pronto Lice Kill System will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

It is not known whether this medicine passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Avoid using other medications or skin products on the areas you treat with Pronto Lice Kill System, unless your doctor tells you to.

Avoid getting this medication in your eyes, nose, mouth, or vagina. If this does happen, rinse with water. Do not use Pronto Lice Kill System on sunburned, windburned, dry, chapped, irritated, or broken skin.

Avoid close contact with others until the infection has been cured. Also avoid sharing hair combs, hair accessories, hats, clothing, bed linens, pillows, and other items of personal use.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using piperonyl butoxide and pyrethrins and call your doctor at once if you have severe stinging, burning, itching, swelling, or irritation where the medication is applied.

Common side effects of Pronto Lice Kill System may include:

• mild itching, burning, or stinging;

• mild skin rash; or

• numbness or tingly feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.