5 mins read

Overview: Pyrethrins/piperonyl butoxide is applied to the skin to treat tiny insects called lice. The most common side effects are red, itchy, or irritated skin. Before using this medicine, tell your healthcare provider if you are allergic to ragweed.

Uses

What is pyrethrins/piperonyl butoxide used for?

Pyrethrins/piperonyl butoxide is commonly used to treat tiny insects called lice that are found on the head, body, or pubic area (sometimes called crabs).

Pyrethrins/piperonyl butoxide may also be used for other conditions as determined by your healthcare provider.

How does pyrethrins/piperonyl butoxide work (mechanism of action)?

Pyrethrins/piperonyl butoxide kills tiny insects, such as lice, by disrupting their nerves and muscles.

How is pyrethrins/piperonyl butoxide supplied (dosage forms)?

Brands and other names

  • A–200
  • LiceOut
  • Pronto
  • R&C
  • Rid
  • Triple X
  • VanaLice

Example dosage forms and strengths

  • 0.3%/3.5% gel
  • 0.3%/3% shampoo
  • 0.33%/4% shampoo

How should I store pyrethrins/piperonyl butoxide?

Some pyrethrins/piperonyl butoxide products should be stored at room temperature, between 68 F to 77 F (20 C to 25 C), and protected from excessive heat and flames. For some pyrethrins/piperonyl butoxide products, storage requirements have not been provided with the product packaging. Most medicines should be kept in a cool, dry location that is out of reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of pyrethrins/piperonyl butoxide?

The most common side effects of pyrethrins/piperonyl butoxide are redness, itching, or irritation where it is applied. Tell your healthcare provider if you have any of these side effects that bother you.

There may be other side effects of pyrethrins/piperonyl butoxide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of pyrethrins/piperonyl butoxide?

While less common, the most serious side effects of pyrethrins/piperonyl butoxide are described below, along with what to do if they happen.

Severe Allergic Reactions. Pyrethrins/piperonyl butoxide may cause allergic reactions, which can be serious. Stop using pyrethrins/piperonyl butoxide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use pyrethrins/piperonyl butoxide?

Allergies to Ingredients. People who are allergic to any of the following should not use pyrethrins/piperonyl butoxide.

  • A–200
  • LiceOut
  • Piperonyl butoxide
  • Pronto
  • Pyrethrins
  • R&C
  • Rid
  • Triple X
  • VanaLice
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific pyrethrins/piperonyl butoxide products they stock.

What should I know about pyrethrins/piperonyl butoxide before using it?

Do not use pyrethrins/piperonyl butoxide unless it has been prescribed to you by a healthcare provider. Use it as prescribed.

Do not share pyrethrins/piperonyl butoxide with other people, even if they have the same condition as you. It may harm them.

Keep pyrethrins/piperonyl butoxide out of the reach of children. If your child requires treatment with pyrethrins/piperonyl butoxide, you or another caregiver should apply the medicine and wash it off for them as directed by your healthcare provider.

Pyrethrins/piperonyl butoxide should only be applied to the skin and hair. Do not get the medicine in your mouth, eyes, eyelashes, eyebrows, ears, nose, lips, or vagina. If you are applying the medicine to your scalp, close your eyes tightly while applying this medicine. If you are applying the medicine to a child’s scalp, you can protect their eyes by covering them with a towel. If the medicine gets into the eyes, gently flush the eyes with water. 

Apply the medicine to dry hair and wash your hands well when you are finished. Leave the product on for ten minutes, then wash the area well with warm water and either soap or shampoo. Dry the area with a towel and then remove the lice and their eggs by following the instructions provided with the medicine. Talk to your pharmacist or other healthcare provider if you are uncertain how to apply this medicine or remove the lice.

Once you have used pyrethrins/piperonyl butoxide, it is important to take other steps to stop the spread of lice. For example, all affected bedding, clothing, hats, and towels should be washed in hot water or dry cleaned. Any affected personal care items, such as brushes, combs, or hair clips, should be washed in hot water. 

In order to kill all lice, you will need to apply this medicine again about seven to ten days after your first treatment. Once you have completed the second treatment, continue to check for lice. If you find live lice more than one week after your second treatment, speak with your healthcare provider about whether you or your child may need to use another medicine.

What should I tell my healthcare provider before using pyrethrins/piperonyl butoxide?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if pyrethrins/piperonyl butoxide is right for you.

In particular, make sure that you discuss any of the following.

Ragweed Allergy. Tell your healthcare provider if you have an allergy to ragweed.

Pregnancy. It is not known if or how pyrethrins/piperonyl butoxide could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant.

Breastfeeding. It is not known if pyrethrins/piperonyl butoxide passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed.

Interactions

Does pyrethrins/piperonyl butoxide interact with foods or drinks?

There are no known interactions between pyrethrins/piperonyl butoxide and foods or drinks.

It is unknown if drinking alcohol will affect pyrethrins/piperonyl butoxide.

Does pyrethrins/piperonyl butoxide interact with other medicines (drug interactions)?

There are no known interactions between pyrethrins/piperonyl butoxide and other medicines. Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much pyrethrins/piperonyl butoxide?

If you or someone else has used too much pyrethrins/piperonyl butoxide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of pyrethrins/piperonyl butoxide?

Pyrethrins/piperonyl butoxide is meant to be applied as two separate treatments about seven to ten days apart. Use it as your healthcare provider recommends. Do not apply extra doses.