Can Lice Cause Hair Loss?

Whether it’s your hair or your child’s head, finding lice is often cause for panic. Where did they come from? Who had them first? Am I going to have to shave my head? Can lice cause hair loss?

While there are many causes of hair loss — genetics, serious illness, autoimmune conditions, chronic hair damage — lice are not typically on the list. In particular, lice infestations cannot activate male pattern hair loss. However, the prolonged presence of lice in your hair (and the symptoms that come with them) can damage your hair and scalp and potentially lead to hair loss if things get out of control.

Luckily, it would take a lot to get to that point, and with proper treatment, you won’t experience any of the hair loss risks of lice infestation. Here’s what you need to know.

Lice infections (also known as Pediculosis capitis) and their symptoms are often misunderstood, so it’s important to know the facts.

People typically get a head lice infestation through close contact with someone who already has head lice. They can spread through direct contact with another person’s infested hair or indirect contact with lice eggs or adult lice if you wear someone else’s hat, scarf, or hoodie, use their hairbrush or comb, or lay on their pillow.

Whether through head contact or sharing hairbrushes, lice can move to a new head of hair extremely quickly and often are hard to detect until the transferred lice start to reproduce and lay eggs. In fact, you may not see lice until the initial invaders have already completed their life cycles and a second generation has been born.

By the way, adult lice lay eggs in both clean and dirty hair, though they may thrive for longer if your scalp and hair hygiene is less than meticulous.

There is no evidence that lice cause hair loss. However, the effects of having lice can thin out your follicles.

The secondary effects of lice — primarily scalp irritation — can damage the hair shaft and cause hair breakage. This damage to your scalp can come from scratching, allergic reactions to head lice products, or the side effects of over-the-counter treatments and their harsh chemicals.

The damage caused by these symptoms and secondary effects is typically temporary, and the hair will grow back over time.

That’s possible because lice do not eat or damage hair follicles — they need your hair to protect them and provide a safe environment for surviving and reproducing.

However, they do create problems down the road because of what they feed on: human blood.

Lice feed on your blood — the same blood your follicles depend on to bring them oxygen and nutrients so they can continue producing more hair shafts.

When your hair follicles are deprived of nutrients and blood, they can become weak, thin, and brittle, increasing the risk of breakage.

So, if lice feed on enough blood, and the resulting scratching becomes severe enough, a lice infestation could interrupt your hair growth cycle.

Telogen effluvium is a type of hair loss caused by an interrupted growth cycle. It's commonly caused by intense stress or trauma to the body and often affects people after surgery or serious illness.

The good news is that telogen effluvium is almost always temporary. Once the underlying cause passes, your hair should bounce back. The bad news is that other symptoms of head lice, like irritation, dryness, and dandruff, could potentially increase your risk of — or cause — a bacterial or fungal scalp infection.

While your scalp can certainly recover from aggressive scratching, an infection can lengthen recovery time — and make the damage worse.

Getting the problem under control prevents more serious complications, so treating lice immediately after discovering them is crucial.

Just make sure that you’re using the right treatments and using them correctly.

A likely reason for signs of hair loss during a head lice infection is irritation or a reaction to the treatment options you’re using — in particular, topical medications, hot water, and lice combs.

Some over-the-counter medicated shampoos and topical treatments can cause skin irritation and an itchy scalp or contain ingredients that can cause allergic reactions. The same goes for any treatments prescribed by a dermatologist.

That’s why it’s important to check labels for any ingredients you might be allergic to and discontinue use if you experience sudden reactions to those topical treatments.

Scalp irritation can come from other places, too. For example, you might irritate your scalp by using excessively hot water to try to wash the lice out.

Even a nit comb (a fine-tooth comb designed to remove lice from hair) can cause irritation if you use it too aggressively or frequently, as follicles may break or snag on the teeth. 

Weak or brittle hair is more likely to break. This can sometimes cause a type of permanent hair loss known as traction alopecia. However, this condition is far more often caused by many years of wearing hairstyles that put stress on the hair’s roots, like tight ponytails, cornrows, plates, and tight buns.

And remember: some hair falls out naturally when you run a comb over your scalp. The average adult loses around 100 follicles a day.

Lice infestations are complicated to deal with, but understanding how they may impact hair growth is simple:

• Lice cannot directly cause hair loss. However, you might experience hair loss and damage from the secondary effects of the infestation and/or the head lice treatment process.

• Hair loss due to lice infestations is easily preventable with proper treatment.

• It’s also often temporary — lice will not cause conditions like male pattern baldness (also known as androgenic alopecia).

• If you notice that your hair isn't growing back after a severe lice infestation or if you see hair loss and have ruled out lice, take action before the problem gets worse.

Genetic hair loss is progressive and irreversible after a point, so the best strategy for maintaining your hairline is early detection and management.

If you’re bouncing back from a head lice infestation or looking for ways to protect your hair daily, consider products like our biotin gummies, volumizing shampoo, volumizing conditioner, and thickening shampoo with saw palmetto. According to some studies, these products support hair health.

We also offer a number of hair loss treatments like minoxidil foam, minoxidil solution, finasteride, and a combination topical finasteride & minoxidil spray.

Reach out today.