Lice are a common concern for families, especially those with school-aged children between 3 and 11 years old.
These tiny, parasitic insects aren’t dangerous and don’t spread disease. Still, a lice infestation can be stressful, disruptive and contagious, which is why it’s helpful to know how to spot, treat and prevent lice to minimize disruptions to your family’s everyday routine.
What Are Lice?
Lice are tiny, wingless insects that live on humans and feed on small amounts of blood.
The most common type affecting children is head lice, found on the scalp and around the ears and neck. Other forms include body lice and pubic lice, but these are less common, particularly in children.
When Is Lice Most Common?
While lice are not seasonal like some viruses, they thrive during times of increased social interaction. Lice can show up any time of year, but outbreaks are more common during:
- Back-to-school season
- Summer camps and sleepovers
- Sports teams and activities involving close contact
These situations all involve children being in close physical contact, creating ideal conditions for lice to transfer easily from one head to another.
Lice infestations are not a result of poor hygiene – they can affect anyone, regardless of age or cleanliness. In the United States, an estimated 6 to 12 million cases occur each year, with most affecting children. This is because children are more likely to have close physical contact with others during play, making it easier for lice to spread.
How Do Lice Spread?
Lice do not jump or fly—they spread through direct head-to-head contact by crawling from one person to another.
They can only survive for about 1-2 days off the human head. Nits (eggs) won’t hatch at room temperature; they need the warmth of the scalp to survive, which is why lice don’t spread easily from surfaces other than human heads.
Lice that fall off a person cannot reproduce or feed, and usually die within 24 to 48 hours.
How Long Do Lice Live?
Lice reproduce quickly, and knowing their life stages helps explain how lice infestations spread. On average, the life cycle of lice lasts about three to four weeks. Here’s more about how lice mature and how long they can live:
Nits (Eggs):
- Tiny, oval eggs that are glued to hair shafts near the scalp
- Often confused with dandruff, but they’re harder to remove
- They hatch in about 7-10 days
Nymphs:
- Immature lice that hatch from nits
- They begin feeding immediately and grow into adults in about 9-12 days
Adult Lice:
- Fully grown, about the size of a sesame seed
- Can live up to 30 days on the scalp and lay 6 to 10 eggs a day
- Females can lay up to 300 eggs in their lifetime
Signs of a Lice Infestation
Be on the lookout for these common signs of lice:
- Persistent itching on the scalp, behind the ears or neck
- A crawling or tickling sensation in the hair
- Nits on the hair shaft, especially near the scalp; Because lice are small and move quickly, nits are often the first sign noticed, especially in good lighting
- Visible lice moving on the scalp
- Red bumps or sores from scratching
How to Treat Lice
Most lice infestations can be treated at home using:
- Over-the-counter (OTC) lice shampoos with permethrin or pyrethrins. Always follow the directions carefully, and avoid using multiple treatments at once to avoid irritating the scalp.
- Prescription treatments (for resistant lice or failed OTC treatments), such as spinosad or ivermectin
- Manual removal using a fine-toothed lice comb to remove live lice and nits. Removal should be repeated every few days for two weeks for the best results.
Most schools no longer follow a ‘no-nit’ policy. Children can often return to school after their first treatment, but it’s always best to check with your school nurse.
It’s a good idea to check and treat all household members who have had close contact with the affected child, even if they don’t show symptoms yet.
How to Clean Your Home if You Find Lice
While lice don’t live long off of the scalp—including on linens, clothing, furniture and bedding—it’s still important to thoroughly clean household items during an infestation. Here are tips for cleaning your home if you find lice on a family member’s scalp:
- Wash clothes, sheets, blankets, and towels in hot water and dry on high heat
- Vacuum carpets, mattresses and furniture
- Seal items that can’t be washed (like stuffed animals) in a plastic bag for 2 weeks
- Soak hair brushes, combs and hair ties in hot water (at least 130°F) for 10 minutes
- Avoid sharing personal hair items during and after treatment
How to Prevent Lice
While lice are common in schools and camps, a few preventive steps can reduce the risk of spreading:
- Teach kids to avoid head-to-head contact, such as touching each other’s heads and hair
- Don’t share hats, scarves, helmets, combs, brushes or headphones
- Check your child’s scalp regularly during high-risk times, such as during summer camp
- Consider using lice-repellent sprays or shampoos with natural ingredients like tea tree or rosemary oil to deter lice (check labels for safety, especially with young children)
When to Seek Professional Help for Lice
Some lice may be resistant to OTC treatments, and a prescription solution or professional advice may be needed. Consider contacting your child’s healthcare provider if:
- You’ve tried over-the-counter treatments, and lice persist after 2 full treatment cycles
- Your child has an allergic reaction or skin irritation from lice products
- You need help choosing the right treatment for your child’s age or hair type
When you act as soon as possible, you can treat lice quickly and prevent future outbreaks, keeping your household healthy and itch-free.
If you’re unsure how to treat a lice infestation—or if it keeps coming back—our Stony Brook Children’s Primary Care providers can help guide you through treatment options and prevention strategies. Learn more or schedule an appointment here for Stony Brook Children’s Primary Care.
