Health Guide
Drug Guide

Pyrethrum extract and piperonyl butoxide (Topical route)


pye-REE-thrum EX-trackt, PIP-er-oh-nil byoo-TOX-ide

Brand Names:

Dosage Forms:






Uses of This Medicine:

Medicine containing pyrethrins is used to treat head, body, and pubic lice infections. This medicine is absorbed by the lice and destroys them by acting on their nervous systems. It does not affect humans in this way. The piperonyl butoxide is included to make the pyrethrins more effective in killing the lice. This combination medicine is known as a pediculicide.

This medicine is available without a prescription.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Although there is no specific information comparing use of pyrethrins and piperonyl butoxide combination in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Older adults

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of pyrethrins and piperonyl butoxide combination medicine in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.


Pregnancy CategoryExplanation
All TrimestersCAnimal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

Pyrethrins and piperonyl butoxide combination medicine usually comes with patient directions. Read them carefully before using this medicine.

Use this medicine only as directed. Do not use more of it and do not use it more often than recommended on the label. To do so may increase the chance of absorption through the skin and the chance of side effects.

Keep pyrethrins and piperonyl butoxide combination medicine away from the mouth and do not inhale it. This medicine is harmful if swallowed or inhaled.

To lessen the chance of inhaling this medicine, apply it in a well-ventilated room (for example, one with free flowing air or with a fan turned on).

Keep this medicine away from the eyes and other mucous membranes, such as the inside of the nose, mouth, or vagina, because it may cause irritation. If you accidentally get some in your eyes, flush them thoroughly with water at once.

Do not apply this medicine to the eyelashes or eyebrows . If they become infected with lice, check with your doctor.

To use the gel or solution form of this medicine:

To use the shampoo form of this medicine:

After rinsing and drying, use a nit removal comb (special fine-toothed comb, usually included with this medicine) to remove the dead lice and eggs (nits) from hair.

Immediately after using this medicine, wash your hands to remove any medicine that may be on them.

This medicine should be used again in 7 to 10 days after the first treatment in order to kill any newly hatched lice.

Lice can easily move from one person to another by close body contact. This can happen also by direct contact with such things as clothing, hats, scarves, bedding, towels, washcloths, hairbrushes and combs, or the hair of infected persons. Therefore, all members of your household should be examined for lice and receive treatment if they are found to be infected.

To use this medicine for pubic (crab) lice:


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Precautions While Using This Medicine:

To prevent reinfection or spreading of the infection to other people, good health habits are also required. These include the following:

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Less common or rare
Skin irritation not present before use of this medicine
skin rash or infection
sneezing (sudden attacks of)
stuffy or runny nose
wheezing or difficulty in breathing

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 10/12/2016

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Thomson & A.D.A.M