Head Lice


Diagnosis, Treatment, and Management of Head Lice 



Human head lice are tiny, wingless ectoparasites that choose humans exclusively for their real estate needs. That means your child can get lice, but your dog cannot. Like all parasites, these human-centered bugs need a host to survive. Some parasites infect the blood or GI tract, but lice prefer to hang out in the yard rather than inside the house. The "ecto" part of being a parasite means your head lice companions only live on the outside of your body. In the case of head lice, it is the hair on your head. Lice infestation is called pediculosis. 


Three types of lice infect humans. In addition to head lice, there are body lice and pubic lice. Each type of lice has evolved to live in its perspective environment. Lice on your head will not infect your body. Lice on your body will stick to your clothes, and pubic lice stay in the pubic region, although in rare cases, pubic lice may find their way to other course hair. Head lice, the most common of the three types, is rarely a cause for concern and will be the primary type covered in this writing.  


Types of Lice 


All lice are parasitic and need a human host to survive. None of the three types can fly or jump and therefore require direct contact to infest another person. Head, body, and pubic lice share the same life cycle: egg (or nit), nymph, and adult. Head lice and body lice are the same genus but different species. Think same household but not the same person. They are kind of like siblings. Public lice, colloquially called crabs, are from a separate family entirely. They are more like a neighbor. All three types of lice are treatable.  


Pubic lice (Pthirus pubis) 


Pubic lice spread through sexual activity and are considered a sexually transmitted infection. Hygiene habits do not affect your chances of contracting pubic lice. Those with good hygiene are just as much at risk of getting it as those with poor hygiene. Pubic lice do not transmit other illnesses, but intense itching can lead to excessive scratching and damaged skin that, in rare cases, may become infected.  


Body lice (Pediculus humanus corporis)  


Body lice, not to be confused with bed bugs, spread when noninfested items such as blankets or clothing come into contact with infested belongings. These tiny pests prefer to spend their time on clothing, climbing onto their human host only when ready to take a blood meal. They are the only type of lice that can transmit other diseases. Lice-borne illnesses often follow body lice outbreaks. Unlike head lice, crowded and unhygienic conditions attract this type of lice.i In the United States, individuals who reside in homeless shelters or other cramped living conditions are at the most significant risk of contracting body lice.  


Head lice (Pediculus humanus capitis) 


Head lice are the most common type of lice and live out their entire lives in human hair. There are six to twelve million cases of head lice every year in the United States, with most of those cases in children between the ages of three and eleven.ii Poor hygiene has no effect on you or your child's chances of becoming infested. Head lice do not care if you bathe regularly or not at all. It spreads from direct head-to-head contact and, less commonly, from sharing hats, brushes, coats, or scarves.




little girl with head lice being combed with a brush drawn image of lice eggs itchy scalp due to head lice Mother removing head lice from her child

Symptoms of Head Lice

Head lice are itchy and embarrassing but not dangerous. Although uncomfortable, there is no reason to panic if your child has head lice. Intense itching is usually as bad as it gets. When lice feed, they inject saliva before dining on your blood. The saliva initiates an allergic reaction, and itching ensues.iii In rare situations, all that scratching can break your skin and results in a secondary infection. 


Some lice infestations, especially if it is your first, are asymptomatic or cause only mild itching. Your body's allergic reaction to the bites may not be as strong. However, the simple act of these unwelcome guests and all six of their legs crawling around can still leave you scratching your head, and not because you're thinking.  


If your child is complaining of an itchy scalp or rubbing their head frequently, take a close look at their hair. You might uncover some visual cues that head lice have found their way onto your kid. Dandruff or other hair product residue can be mistaken for lice eggs, but eggs remain close to the scalp and will not wash out.  


Although there are over-the-counter medications for ridding yourself of head lice, consulting a doctor is a good choice for accurate diagnosis and treatment if you suspect lice. A trained physician can examine pictures or videos and evaluate symptoms to determine if your suspicions are correct. They can recommend the best course of treatment based on your child's age and the severity of infestation. 

Lifecycle of Headlice 


According to the CDC, head lice go through three phases during their lifetime.iv The initial stage is an egg, followed by the nymph, and then finally an adult. The entire lifecycle exists only in human hair, which can be long or short. Hair only needs to be long enough to support the eggs, which require about a fourth inch of length.   


Nit (Egg) 


The youngest form of lice is the egg, also known as a nit. Nits are hard to see and can easily be mistaken for dandruff. An adult female will lay her nits at the base of the hair, where it will stay warm, around a fourth of an inch from the scalp. The female louse affixes her nit to the shaft of the hair, ensuring it is safe and secure for the next six to nine days until it hatches. Nits are oval-shaped and 0.8 mm long. Once hatched, nit casings remain attached to the hair but are more obvious to spot due to a color change.  




Nymph is the next phase of the head lice lifecycle. Upon hatching, nymphs have all the same features as their adult counterparts but are much smaller, starting about the size of a pinhead. Nymphs go through three stages, shedding their skin each time before becoming an adult about seven days after hatching.  




Once fully grown, an adult louse will be about the size of a sesame seed and similar in color. Females are larger than males, and both sexes will appear darker on individuals with darker hair. They have six legs with claws on each to grasp the hair and move about their environment.  


Females can lay roughly six nits per day and live an average of 30 days. That means female lice can lay up to 180 nits in their lifetime. Adults need to feed multiple times per day and do not live long if they are not in their preferred habitat. If not safely roaming about your hair, lice will die within two days without a blood meal.  


How is Lice Transmitted?  


Lice can only move by crawling. They travel most efficiently using their clawed legs to grip hair and maneuver around. They cannot fly and do not jump, nor live long off the human head. Close and consistent contact is usually required for lice to spread from child to child. In most cases, direct head-to-head contact is necessary. Less typically, sharing hats, clothing, or brushes may spread lice.  


Most lice that find their way to your clothes are too weak to hold onto your hair, indicating they are sick or elderly and unlikely to infect others.v Activities like hugging and cuddling allow healthy lice to crawl from one head to the other, which is a far more efficient mode of transmission than from shared clothing.  


Some studies have shown that girls are more likely to get head lice than boys. Although their long hair is a common conclusion for this, a more likely scenario is that girls engage in closer physical contact than Additionally, lice happily exist in short hair. Lice usually stay close to the scalp where it is warm and their food supply is nearby. They do not need long hair for that.  

Diagnosing Head Lice Infestation 


Head lice misdiagnosis. Anyone without experience can easily mistake dandruff or other dried hair products for lice. The best way to determine if someone is infested is to look for lice moving within the hair. You should see them crawling around before assuming your child has an infestation. However, seeing active lice can be challenging, especially in milder cases. They move fast to avoid light. If you pull out the flashlight to inspect your child's itchy head, you might not see anything if all the lice scatter into the shadows.  


Sometimes using a magnifying glass along with a flashlight can increase your chances of seeing these tiny ectoparasites. Although lice are big enough to be seen by the naked eye, about the size of a sesame seed, a magnifying glass can be a helpful tool. Some physicians may use a Wood's light, which illuminates the lice when used in a dark room.vii Most doctors can diagnose infestations without any unique light sources.  


You can also check for nits. Even though nits without active lice do not indicate a current infection, it gives you some information to bring to your doctor. Unlike dandruff or hair product buildup, nits are secured to the hair shaft no more than one-fourth inch from the scalp. Nits without live lice indicate an old and no longer active infestation. These do not require treatment. 


Contact a doctor if you suspect your child has lice. Take pictures and videos of anything you see and document your child's symptoms. You have several treatment options that will change depending on your child's age. Your doctor will be able to diagnose lice, develop a care plan, and provide any necessary prescriptions.  


How to Treat Head Lice

You do not need to worry about catching other illnesses from your unwelcome residents, but you do need to evict them. Fortunately, there are several effective treatment options, and many of them only require one application. All household members should be screened for head lice. Anyone who has an active infestation will need treatment. Those who are not infested do not need prophylaxis. Although shaving your child's head is an effective way to eradicate lice, it is unnecessary. The embarrassment of a shaved head, particularly in girls, far exceeds any benefit from such an extreme reaction.  


Blankets, Linens, and Stuffed Animals Exposed to Head Lice 


Before initiating treatment, wash all bed linens, clothes, and stuffed animals that have come into contact with the infected individual. There is no need to do anything beyond setting your washer and dryer to the hot setting. Lice and their nits are killed when exposed to temperatures of 128.3 degrees Fahrenheit for a minimum of five minutes.viii Items that cannot be laundered can be sealed in a plastic bag for two weeks or soaked in hot water for 10 minutes.  


For furniture, rugs, or carpet, a quick vacuum will suffice. Remember, lice do not spread easily without direct head-to-head contact. It is unnecessary to use fumigant sprays because lice are not that resilient once they have lost the protection of your hair. Fumigating your house would be a massive overreaction to something that is more of a nuisance than anything else.  


Ovicidal Versus Non-Ovicidal Medications 


After tossing a load of laundry in and soaking hairbrushes in hot water, you can start treating the individual with head lice. There are several over-the-counter and prescription pediculicides (medicines that kill lice). Pediculicides come in two varieties: ovicidal and non or weak ovicidal. An ovicidal will kill nits, while the non or weak ovicidal will only kill the nymphs and adults.  


Non or weak ovicidal pediculicides require a second application nine to ten days after the first to kill any lice hatched after the initial treatment. Ovicidal pediculicides usually require just one use because they kill active lice and their nits. Your doctor will help you determine the best medication for your situation.  


Over-the-Counter Lice Treatment 


Pyrethrin is a type of head lice medication extracted from a species of flowers from the chrysanthemum family. Pyrethrin is combined with piperonyl butoxide to make the medicine more lethal to lice. Permethrin lotion 1% is similar to pyrethrin; however, it is manufactured in a lab rather than extracted from a flower. Both types of medications are non or weak ovicidal, and FDA approved for children two and older. 


Prescription Lice Treatment 


Benzyl alcohol lotion, 5%, is a non-ovicidal formula approved for children as young as six months of age. Because of its non-ovicidal status, second treatments are often necessary.  


Ivermectin lotion, 0.5%, is also non-ovicidal, but it seems to prevent newly hatched nymphs from surviving. Therefore second treatments are rarely needed. Ivermectin lotion, 0.5%, is approved for children six months and older.  


Malathion lotion, 0.5%, is a partial ovicidal and requires a second treatment only if active lice are spotted after seven to nine days. This medication is approved for children six years and older.  


Spinosad 0.9% topical suspension is an effective ovicidal that does not require retreatment when used correctly. Spinosad 0.9% topical suspension is approved for children as young as six months old.  


Nit Comb 


A nit comb is a small comb with thinly spaced teeth designed to pull lice eggs (nits) and lice out of hair. Using a nit comb can be helpful when utilized along with lice shampoo, especially with non or weak ovicidal shampoos. Nit combs as the only method of lice removal is usually ineffective.  


How do You Know if Head Lice Medication Worked?  


Whether the medication you chose was purchased at your local grocery store or prescribed by your doctor, follow the instructions. Each product will have clear directions provided with the package. Contact your doctor for clarification if you do not understand the package insert. Be aware that longer hair may require a larger dose, not a stronger prescription, to ensure all hair is covered.  


Check your child's hair around eight to twelve hours after completing head lice treatment. You should see mostly dead lice with the possibility of a few slow-moving ones. If you do not see any dead lice and they are still actively enjoying life on your child's head, you may need a different medication. Do not treat again. Your lice may be resistant to the medicine you used. Consult your healthcare provider to determine your best option moving forward.  


Retreatment is necessary seven to nine days after the first round when using non or weak ovicidal shampoos. Other medications may require retreatment only if live lice are still present after one week. The instructions for your lice shampoo will tell you whether you will need more than one application. Each medication has different requirements. If you are unclear about how yours works, your doctor is available to help.  


No Nit Policy 


A no nit policy is a policy in which children are removed promptly from class if infected with lice and not allowed to return until no nits are present in the child's hair. This policy is likely ineffective at preventing the spread of lice and is not supported by the American Academy of Pediatrics or the National Association of School Nurses.ix Here is why:  


• Many visible nits are too far from the scalp to be viable 

• Nits are attached to the shaft of the hair and do not come off and infest other children 

• Other hair residues can easily be mistaken for lice or nits 

• Nits are often identified by school officials and not healthcare professionals increasing the chances of misdiagnosis 


No nit policies are based on a misunderstanding of lice and how they are transmitted. Lice are not dangerous, do not spread disease, and require relatively close and consistent contact to get from your child to another. Children identified at school as having lice should be allowed to finish the day and return after treatment has started.  

Virtual Appointments for Head Lice Diagnosis and Treatment

If you think you have lice, don't be alarmed. Lice infestations are not a big deal. It is itchy, creepy, and no one wants it. But it is not dangerous. Lice will not transmit disease and are harder to spread than you think. It is easy to treat and clears up quickly. Maybe not quick enough if it is your head they have found, but you can usually get most of these wingless parasites killed within a day.  


If someone in your household has lice check everyone else for it, but you can skip your furry family members. Pets cannot get lice. Any member without an infestation can forgo the medicated shampoo. The house does not need to be turned upside down, looking for every last louse that might have made its way to the couch. Lice are not happy unless they are inhabiting human hair, and if they can't hold on to your hair, they are probably too weak to set up a party in someone else's.  


We know your time is limited and that you can't spend it worrying about a few bugs that have taken over your kid's hair. Our skilled doctors can quickly diagnose and treat your lice with a quick and easy virtual appointment. You don't have to wait until Monday to schedule a visit or drag your lice to a doctor's office. Instead, take care of this harmless pest in the comfort of your own home and contact us today. 

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