Super Lice Cases Are on the Rise: Here’s What You Should Know

Lice are insects that eat human blood. There are different types of lice like head lice, which attach to hair follicles on the scalp, and sometimes the eyebrows and eyelashes. Lice can pass from person to person, and lice outbreaks are common in schools and daycare centers. In recent years, lice have become more difficult to get rid of because they’ve built resistance to pyrethroids. These are known as super lice.

Pyrethroids are found in over-the-counter (OTC) lice treatments, but they don’t always work. If you want to get rid of super lice fast, you may have to try alternative or more direct treatments.

What are super lice?

Super lice have been found in the U.S. since the mid-1990s. What makes them “super” has nothing to do with any of their strength, speed, numbers, or the symptoms they cause. Instead, they’re simply super because they don’t respond to pyrethroids. 

Pyrethroids are a class of medication that are toxic to lice. Pyrethroids are the synthetic version of pyrethrins, a natural pesticide. Pyrethroids, in the form of permethrin, are the active ingredient in some OTC lice treatment products, like Nix, Rid, and Elimite. 

Super lice aren’t more itchy or painful than regular lice. They don’t spread any diseases or do any long-term damage. But they’re harder to eliminate. People often need multiple rounds of treatment to get rid of super lice. 

How do lice become resistant to treatment?

Super lice are resistant to some medications because of a mutation in one of their genes. This mutation allows them to escape the toxic effects of pyrethroids. This gene mutation likely evolved by chance, but now it offers a survival advantage. 

Pyrethroids are the top treatment options for lice. But it doesn’t always kill 100% of the lice population. Lice that can outlive pyrethroids go on to have babies and pass on the genes for resistance, creating a super lice population boom.

How can you tell if you have regular lice or super lice?

Super lice don’t look any different from regular lice. You can’t know if you have super lice just by looking at them. Laboratories don’t routinely offer genetic testing for lice. So you won’t know you have super lice until you try treatment and it doesn’t work.

There’s no official diagnosis for super lice. But in general, if your lice hasn’t gone away after two rounds of treatment, then you may have a case of super lice. 

Super lice have popped up in many areas in the U.S. But it’s not clear how common super lice are because of “pseudo-resistance.” Pseudo-resistance describes a situation where lice don’t go away after treatment, but there’s no clear evidence of genetic mutations among the lice. Pseudo-resistance can happen if lice treatment isn’t used correctly or people get lice back to back. 

See a healthcare professional if you’ve tried treating your lice at home and they haven’t gone away. Whether you have super lice or simply very stubborn lice, there are other treatments that can help. 

How do you treat super lice?

Not all head lice treatments have pyrethroids in them. There are several medications available that use other chemicals to kill lice. And super lice haven’t developed resistance to these medications yet — at least not in large numbers. 

Here are some options you can try:

• Malathion (Ovide): The topical medication malathion (Ovide) is approved by the FDA and kills live lice and some lice eggs. You should spread it in your dry hair until wet and leave it in for 8-12 hours until dry again. You’ll need to comb your hair for nits after rinsing out the ointment. Some cases show head lice to be resistant to malathion, but more clinical evidence is needed to show lice’s full resistance to this medication.

• Ivermectin (Sklice): Another ointment, ivermectin (Sklice) kills live lice but not eggs. You put it in your hair for 10 minutes and then wait 24 hours to shampoo it out. As with certain other topical medications, you’ll want to comb out the dead lice and nits. 

• Spinosad (Natroba): This treatment targets live lice. You’ll spread a bottle of spinosad (Natroba) in your hair and leave it in for 10 minutes before you shampoo it out. Unlike with malathion and ivermectin, you don’t need to comb out the nits after you use it.

You may need a prescription from your healthcare professional for these treatment options. 

Natural remedies for super lice

There are other things you can do to treat super lice without using prescription medication. These tips are especially helpful for children younger than 2 years, since they’re too young to use many medication options. Note that while medications tend to have a more immediate effect with little effort, natural options are more labor-intensive and can take longer to work:

• Wet-combing: Comb the eggs or nits out every night. You’ll likely still have to comb out the dead lice and nits with any medication you use.

• Heat therapy: Heat therapy consists of a 30 minute application of hot air to kill head lice. 

How can you prevent getting super lice? 

There’s no way to completely avoid super lice. Because they look and act like regular lice, you can’t take action that would target only super lice. The best way to prevent lice, including super lice, is never to share anything that touches your hair with anyone else. This will keep you from coming in contact with nearby lice.

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Written by:

Dean Shaban, MFA

Dean Shaban is a writer, editor, professor, and photographer based in Washington, D.C. After a year at WebMD, Dean joined GoodRx as a Health Editor in January 2024. He has a combined 7 years of experience in editorial and teaching.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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