Spinosad Treatment for Lice Infestations - How It Works, Safety, Cost

Understanding Lice and Spinosad Treatment

Lice are tiny parasitic insects that live on the scalp and feed on human blood. They are highly contagious and spread easily through head-to-head contact and sharing personal items like hats, helmets, hairbrushes, towels, and bedding. Lice attach their nits (eggs) to strands of hair close to the scalp where the warmth helps them hatch in 7-10 days. Once hatched, lice reach maturity in about 7-12 days and can lay up to 10 eggs per day. This rapid reproduction cycle allows lice infestations to quickly get out of control.

Lice infestations are common in children ages 3-11 years old. Transmission most often occurs by direct head-to-head contact at school, sleepovers, sports activities, camp, and play dates. Symptoms include an itchy scalp and the presence of small grayish-white eggs firmly attached to the hair shaft. Diagnosis is made by finding live lice or eggs during a comb through of damp hair.

Treating and Preventing Lice

There are several over-the-counter and prescription treatment options available. The most common over-the-counter remedies contain the active ingredients permethrin (Nix) or pyrethrins with piperonyl butoxide (Rid). These products work by paralyzing and killing live lice. However, neither chemical kills 100% of eggs, so a second treatment is recommended 7-10 days later to kill newly hatched lice. These products are generally safe when used as directed.

Prescription products like spinosad (Natroba) and benzyl alcohol (Ulesfia) have also been shown to be safe and effective for treating head lice. Spinosad comes in topical suspension form and is approved by the FDA for treating children 6 months of age and older. It works by attacking the nervous system of lice in a unique way that causes them to die before they are able to lay eggs. This helps break the reproduction cycle and prevent reinfestation.

What is Spinosad?

Spinosad is derived from a naturally occurring soil bacterium called Saccharopolyspora spinosa. It was discovered in the 1980s and introduced as an agricultural insecticide before being developed into a pharmaceutical treatment for lice. The bacteria produce spinosyn A and spinosyn D metabolites, which have insecticidal properties against a wide variety of pests. When concentrated and purified, these metabolites are combined to create the active ingredient spinosad.

How Does Spinosad Work?

Spinosad has a unique mechanism of action that is different from traditional lice treatments. It activates nicotinic acetylcholine receptors, which excessive stimulates the nervous system of lice. This causes tremors, paralysis, and ultimately death before lice are able to lay a significant number of eggs. By killing lice before they reproduce, spinosad is able to stop the life cycle and prevent reinfestation after just one application in most cases.

Spinosad also has ovicidal activity, meaning it can penetrate the shell of lice eggs and kill some developing larvae. This decreases the need for repeat applications. Spinosad begins working quickly and kills lice within a day of application. The single retreatment option covers any newly hatched lice before they are able to reach maturity and reproduce.

Efficacy of Spinosad for Lice

Spinosad has been proven highly effective at eliminating head lice. In clinical trials, a single application of spinosad resulted in 70-91% effectiveness compared to just 25% with a placebo. After a second application 7 days later, the cure rate with spinosad was over 98%.

A study published in the Pediatric Infectious Disease Journal found spinosad eliminated lice in 84% of participants after two applications, compared to just 43% effectiveness with permethrin. Spinosad was also better tolerated than permethrin.

Research has shown spinosad to be effective against lice resistant to traditional pyrethrin and pyrethroid class medications like permethrin. This makes it a good alternative when treatment failure occurs with over-the-counter remedies.

Using Spinosad for Lice Treatment

Spinosad is available as a topical suspension typically containing 0.9% active ingredient. It is available by prescription under the brand name Natroba. Spinosad should be applied to dry hair until the scalp and roots are completely saturated. The hair should then be thoroughly combed with a nit comb to remove lice and eggs.

The scalp should be washed with regular shampoo after 10 minutes. The treatment is then repeated at 7 days to kill any newly hatched lice. One 60mL bottle of spinosad is usually adequate for short and medium length hair. Those with long or thick hair may require two bottles.

Spinosad should be applied in a well-ventilated area away from the eyes, nose, and mouth. Contact with eyes should be avoided. People treating children should wear gloves to minimize contact. Spinosad has a short half-life and degrades rapidly in sunlight.

Treatment Considerations with Spinosad

Spinosad is approved for children as young as 6 months old. It can be used in kids, teens, and adults, including the elderly. The ingredients do not cause scalp irritation or allergy like traditional lice medications sometimes can. Spinosad has not been tested in pregnant or nursing women, so it should be avoided or used under medical supervision in this group.

The short half-life and ovicidal activity of spinosad allows successful lice eradication with just one or two applications in most patients. This leads to better treatment compliance compared to products that require repeat applications over weeks.

While a small portion of individuals still require a third application, studies show spinosad results in a high cure rate of around 99% after no more than three treatments. The risk of resistance developing to spinosad is low when directions are properly followed.

Side Effects and Safety

Spinosad has demonstrated a good safety profile in clinical testing. Potential side effects are generally mild. Most common are scalp redness, irritation, and dried out hair. These effects generally resolve quickly after treatment ends.

Less than 1% of those treated with spinosad developed eye redness or irritation. Spinosad should be kept away from the eyes during application. There is a small risk of respiratory irritation if inhaled, so use in a well-ventilated area is recommended.

Neurologic effects like dizziness, vertigo, and headaches are possible but very uncommon. Contact a physician if concerning neurologic symptoms develop. Spinosad has a pregnancy category B rating, indicating it is likely low risk during pregnancy but should be used with care.

Other Lice Treatment Tips

In addition to spinosad medication, there are some other things that can be done to treat and prevent the spread of lice:

• Use a fine-toothed lice comb or nit comb to remove lice eggs from the hair shaft.
• Monitor close contacts like family members for signs of lice and treat if infested.
• Avoid direct head contact and sharing personal items like brushes and hats during an infestation.
• Wash linens, pillowcases, towels on hot water and dry on high heat.
• Items that can't be washed should be bagged for 2 weeks to kill lice.
• Vacuum carpets, furniture, car seats used by infested person.
• Soak combs and hair accessories in rubbing alcohol or hot water for at least 10 minutes.

Lice are very common in kids. Despite being annoying, they do not pose serious health risks. While eradicating lice requires diligence, spinosad provides a safe and effective treatment option.

Using a two-treatment approach with spinosad along with combing and environmental cleaning can successfully eliminate a lice infestation in most cases. Be sure to check everyone in close contact with the infested person and treat any other family members found to be affected to prevent retransmission.

Frequently Asked Questions

How do you know if you have lice?

Signs of a lice infestation include an itchy scalp, the presence of live lice seen moving on the scalp or in the hair, and small whitish eggs (nits) firmly attached to the hair shaft near the scalp. Diagnosis is made by finding live lice or eggs during a thorough inspection of the scalp and hair.

Are lice dangerous?

Lice are not dangerous and do not transmit disease or illness. They are mainly an annoyance that causes itching. Head lice feed on tiny amounts of blood from the scalp but do not cause significant blood loss. Scratching can sometimes lead to skin irritation and secondary bacterial infections.

Where do lice come from?

Lice are spread by direct head-to-head contact with an infected person. Less commonly, they can spread via contact with personal items like combs, brushes, hats, helmets, towels, bedding, or upholstery that has recently been used by someone with lice.

How quickly do lice spread?

Lice are highly contagious and transmission commonly occurs during close physical contact. At school, daycare, sports, or other activities, it's easy for crawling lice to move between children playing closely together. Lice can also spread rapidly within families or households.

How do you use spinosad for lice?

Spinosad suspensions should be applied thoroughly to dry hair and allowed to sit for 10 minutes before rinsing out with regular shampoo. Hair should then be combed with a nit comb. Treatment is repeated at 7 days. One bottle is usually sufficient for short to medium length hair while two may be needed for long or thick hair.

Is spinosad better than permethrin?

Clinical studies have shown spinosad results in higher cure rates for lice infestation than permethrin. Spinosad is also effective against lice resistant to permethrin. The ovicidal activity of spinosad decreases the need for repeat treatments compared to permethrin.

Is spinosad OTC or prescription?

Spinosad is available by prescription under the brand name Natroba. Over-the-counter products that contain spinosad are not currently available. A prescription is required and spinosad is usually covered by insurance if prescribed for a lice infestation.

Is spinosad safe for kids?

Spinosad is considered safe for children as young as 6 months old. It results in few side effects beyond minor scalp irritation in some users. Spinosad carries a pregnancy category B rating, meaning it is considered low risk during pregnancy.

How much does spinosad cost?

The cost for spinosad depends on whether you have prescription insurance coverage. With insurance, spinosad typically costs between $50-100. The retail cost is around $150-250 without insurance. Some pharmacies like Costco offer spinosad at discounted prices.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.