Can Cold Kill Lice? What You Should Know About Freezing

There is no simple or quick fix for lice. Not even freezing temperatures can guarantee their elimination. Yes, extreme temperatures can sometimes harm lice, but it’s not so easy to actually expose them to these conditions. Cold is especially complicated, as what seems cold to most humans might not be a big deal to the lice already protected by the human scalp.

A lot depends on the location of the lice at the time they’re hit with cold temperatures. On the head, they remain fully protected by body heat. Elsewhere, however, cold might help kill them, or, at least, kill them faster.

Knowing the effects of cold (or often, lack thereof) is key to using it appropriately to deal with lice. Keep reading to learn how lice and nits are impacted by cold temperatures — and to discover the most effective strategies for getting rid of them.

Does Cold Kill Lice?

Cold temperatures are unlikely to kill lice if they are already present on the human head. Its impact is limited because humans are warm-blooded, with internal temperatures generally around 98 degrees Fahrenheit. Skin temperatures fluctuate a bit more, but the scalp generally stays quite warm even as weather conditions change. Yes, your head might feel cold on a frigid winter’s day — but to the lice or nits on your scalp or in your hair, it remains a warm and even protective environment.

If anything, new infections are more likely when cold weather strikes, although the spread of lice mostly involves head-to-head contact. Still, hats and scarves spread lice if shared. These winter essentials can be stored in freezers to kill lice, but they must remain in the freezer for multiple days to be safe.

For a current lice infestation, cold is not a safe or reliable option. Stick with manual removal and, if you need extra help, add a non-toxic over-the-counter product. Better yet, let professional technicians do the work, as they know exactly what lice and nits look like — and what actually kills them.

What Cold Temperature Kills Lice?

Lice can be killed by temperatures of under 5 degrees Fahrenheit, but not immediately — at this temperature, it takes a full ten hours of exposure to kill both lice and nits. A quick chill accomplishes little; with cold, exposure time is the deciding factor.

Keep in mind that what seems cold might not actually be cold enough. This is true even when keeping potentially exposed objects (like hair accessories) in the freezer. While many freezers are set at 0°F or lower, they could potentially be warmer, depending on ventilation or the quality of the door seal. If using freezers as a strategy for dealing with lice, it’s important to confirm that they actually run cold enough to make a difference.

It’s worth noting that, regardless of temperature, lice don’t survive long away from the human head. Once removed from the scalp or hair, lice typically die in 24 or 48 hours. Cold can expedite this a bit, but dehydration is the deciding factor. Simply put, if lice can’t feed and if they can’t retain moisture, they can’t survive for long.

Ultimately, the ideal treatment is the one that actually kills both lice and nits without causing harm to the human host. With that in mind, cold exposure should only be used as a strategy for killing lice on objects such as hair accessories. It is not a safe option or effective for dealing with lice on humans.

Can Nits Survive the Cold?

Often mistaken for dandruff, nits are tiny and can be difficult to spot. They’re shaped like teardrops and about the size of a pinhead. Don’t let their small size fool you; nits are sturdier than they look and clearly built for survival. They are shielded by protective shells and also cemented to the hair shaft near the human scalp — a consistent source of warmth and moisture. Cold weather has little effect; as long as nits remain close to the scalp, they can survive until they hatch.

Even if nits are killed by over-the-counter products or other strategies, their non-viable eggs can remain on the scalp indefinitely. A fine-toothed comb can be used to physically remove them, and, once off the head, they’re far less of a threat. They cannot hatch, after all, without the warmth and moisture of the human scalp and once hatched, they can only survive if they can feed on human blood.

Can Lice Survive in the Cold?

Winter does not end the lice season. In fact, many communities see worse infestations during the winter. This is when school is in session and when kids may be in close contact during the day. While lice mostly spread through direct, head-to-head contact, winter hats provide yet another way for lice to spread, especially if those hats are shared among kids. Generally, cold weather has little impact one way or another, so preferred approaches to killing lice won’t differ a great deal as the temperature outside fluctuates.

Does Cold Water Kill Lice?

Water does not kill lice. This may be surprising, but again, lice, nymphs, and lice eggs can handle a lot if they find refuge near the human scalp. They can survive underwater for hours, so long as they are tightly clamped to hair shafts. A short shower or even a few hours in the pool are unlikely to make a difference. In fact, some studies show that lice can survive up to 24 hours submerged in water. During that time, their metabolism slows and their respiratory openings close.

The temperature of the water has little effect, other than risking the comfort or safety of the lice’s human hosts. The good news is, that while water is not a solution, it’s also generally not a vehicle for transmission. If lice spread near cold water, it’s through head-to-head contact, or, in rare situations, through shared towels.

Cold packs aren’t helpful either and can actually cause harm if applied for too long. For lice to be harmed by the cold, exposure needs to continue for at least ten hours and likely far longer.

When Freezing Can Kill Lice

Cold exposure is not a safe or realistic option for removing lice from the scalp or hair. However, there are other ways to use cold temperatures to treat or prevent lice. If you’re dealing with lice on fragile objects, your freezer could actually be quite helpful.

This approach is best reserved for items that cannot realistically be washed in hot water (or, at least, without risking damage). Examples include hair accessories (like hair ties or headbands) along with stuffed animals or decorative pillows.

If using cold as a strategy for killing lice, focus on length of exposure. A few minutes or even hours in the freezer won’t cut it; at minimum, lice (or items that could contain lice) must be frozen for ten hours. When in doubt, seal items in a plastic bag and keep them in the freezer for over a week (or two weeks to be safe). Otherwise, you can also take potentially compromised items to your local dry cleaner.

Cleaning can help, but it offers no guarantees, since it does little to address the real problem that allows lice to spread: direct contact. There’s no harm in washing bedding or vacuuming the carpet or rug where someone’s head may have rested — but extreme cleaning and fumigant sprays are best avoided.

Is Heat or Cold Better for Bedding and Clothes?

While cold can be helpful for items that are vulnerable to damage, heat is generally the better option when dealing with bedding, towels, and most clothing items. This is as simple as washing items in hot water — ideally 130°F or hotter. Next, dry items, using a high heat setting.

Heat can also be helpful for many combs and hairbrushes. Simply soak these in hot water for ten minutes. If those combs or brushes are used on someone with an active infestation, it’s best to avoid sharing them.

What Actually Gets Rid of Head Lice?

Many treatments promise to end frustrating lice infestations or prevent them in the first place. When you’re worried about lice, products that promise quick results seem compelling — but what appears to eradicate lice in the moment could cause side effects or may not actually solve the problem in the long run.

Lindane is a relevant example of this. Insecticides were once the go-to solution for getting rid of lice, but they are no longer a first-line option. Yes, these products are toxic to lice, but unfortunately, they can also be harmful for humans, prompting serious side effects.

Home remedies like olive oil or tea tree oil may be tempting, but there is little proof that these actually help — and applied incorrectly, some home remedies can actually be dangerous.

When exploring potential treatments, consider the long-term impact. Solutions that appear to get rid of lice in the moment might not keep infestations away for good. Nits can survive many conditions that kill adult lice, so, once they hatch, the lice will return.

Manual removal is the most effective, so long as it’s thorough. It can be complemented by over-the-counter products (like permethrin or pyrethrin) or prescriptions, including creams or shampoos.

Get In-Home Lice Removal With Lice Happens

Why leave lice removal up to chance when experts can guide you through the process? At Lice Happens, we understand how stressful it is to deal with lice, but we also recognize the importance of tackling them the right way with patience and precision. This means skipping the excess cleaning and ineffective (or dangerous) treatments involving extreme temperatures. Why take unnecessary risks or put in extra effort when these quick fixes don’t actually work?

We offer convenient nit removal and screening services right in your home, where our technicians work hard to remove all lice and to educate you (and your loved ones) about prevention. Our customers may feel panicked when they call, but, once they work with our technicians, they’re relieved and confident about keeping lice away. Find a technician near you or browse products that help you remain lice-free.