What is Malathion: Uses, Dosage, Side Effects and More

Malathion is a prescription medication that comes as a lotion specifically designed to treat head lice infestations. This topical treatment works by targeting the nervous system of lice, effectively eliminating both adult lice and their eggs (nits) from your scalp and hair. While the idea of using a medication to treat lice might feel overwhelming, malathion has been safely used for decades and offers an effective solution when other treatments haven't worked.

What is Malathion?

Malathion is an organophosphate insecticide that's been specially formulated for safe use on human hair and scalp. Unlike the agricultural version of this chemical, the topical form contains a much lower concentration and includes ingredients that make it gentler on your skin. The medication comes as a lotion that you apply directly to dry hair and scalp.

This prescription treatment belongs to a class of medications called pediculicides, which are specifically designed to eliminate lice. Your doctor will typically recommend malathion when over-the-counter lice treatments haven't been effective, or when you're dealing with a particularly stubborn infestation.

What is Malathion Used For?

Malathion is primarily used to treat head lice infestations in adults and children over 6 years old. Head lice are tiny insects that live on the scalp and feed on blood, causing itching and discomfort. These parasites spread easily through close contact, making them common in schools, daycares, and households.

Your doctor might recommend malathion if you've tried other lice treatments without success. It's particularly effective against lice that have developed resistance to other medications like permethrin or pyrethrin-based treatments. The medication targets both live lice and their eggs, helping to break the cycle of infestation.

How Does Malathion Work?

Malathion works by interfering with the nervous system of lice, causing paralysis and death. The medication blocks an enzyme called acetylcholinesterase, which is essential for proper nerve function in insects. This action is much more toxic to lice than to humans because our bodies process and eliminate the medication differently.

The lotion also helps suffocate lice by coating them and their eggs with an oily film. This dual action makes malathion particularly effective, even against lice that have become resistant to other treatments. The medication continues working for several hours after application, ensuring thorough elimination of the infestation.

How Should I Take Malathion?

Apply malathion lotion to completely dry hair and scalp - never use it on wet hair as this can increase absorption into your skin. Start by parting your hair into sections and applying the lotion thoroughly from the roots to the tips, making sure to cover all areas of the scalp. You'll need enough lotion to saturate your hair completely, which typically requires most or all of one bottle.

After application, allow your hair to air dry naturally - never use a hair dryer, curling iron, or any heat source while the medication is in your hair. The lotion contains alcohol, which makes it flammable. Once your hair is completely dry, cover it with a shower cap or towel and leave the medication on for 8 to 12 hours, preferably overnight.

The next morning, wash your hair with regular shampoo and warm water. Use a fine-toothed comb to remove dead lice and nits from your hair. If you still find live lice after 7 to 9 days, you may need a second treatment, but never apply malathion more frequently than your doctor recommends.

How Long Should I Take Malathion For?

Most people need only one treatment with malathion to eliminate their lice infestation completely. The medication is designed to kill both adult lice and their eggs in a single application when used properly. However, your doctor might recommend a second treatment if live lice are still present 7 to 9 days after the first application.

You should avoid using malathion for more than two treatments without consulting your doctor. If the infestation persists after two properly applied treatments, your healthcare provider will need to evaluate whether you're dealing with resistant lice or if there's another underlying issue. Sometimes, what appears to be treatment failure is actually re-infestation from close contacts who haven't been treated.

What Are the Side Effects of Malathion?

Most people tolerate malathion well, but like any medication, it can cause side effects. The most common reactions are mild and occur at the application site. Understanding what to expect can help you use the medication safely and know when to contact your doctor.

Common side effects that many people experience include:

• Mild skin irritation or redness at the application site
• Temporary stinging or burning sensation on the scalp
• Dry or flaky scalp after treatment
• Mild headache during or after application
• Temporary hair texture changes

These reactions typically resolve on their own within a few days and don't require medical attention unless they become severe or persist.

More serious side effects are rare but require immediate medical attention. Contact your doctor right away if you experience:

• Severe skin reactions like blistering, swelling, or intense burning
• Difficulty breathing or wheezing
• Severe headache or dizziness
• Nausea or vomiting
• Muscle weakness or twitching
• Excessive sweating or drooling

These symptoms could indicate an allergic reaction or absorption of too much medication into your system, both of which need prompt medical evaluation.

Who Should Not Take Malathion?

Malathion isn't safe for everyone, and certain groups of people should avoid this medication entirely. Never use malathion on infants or children under 6 years old, as their skin absorbs medications more readily than adults. The safety profile in very young children hasn't been established, making other treatment options more appropriate.

You should also avoid malathion if you're pregnant or breastfeeding. While there's limited data on how the medication affects developing babies, it's better to choose safer alternatives during these sensitive times. Your doctor can recommend pregnancy-safe lice treatments that won't put you or your baby at risk.

People with certain health conditions need special consideration before using malathion. Avoid this medication if you have:

• Known allergies to organophosphate compounds
• Severe asthma or breathing problems
• Open wounds or severely irritated skin on your scalp
• History of seizures or neurological disorders
• Liver or kidney disease

Additionally, if you're taking certain medications, especially those that affect your nervous system, malathion might not be appropriate for you. Always tell your doctor about all medications and supplements you're taking before starting treatment.

Malathion Brand Names

The most common brand name for malathion lotion is Ovide, which is the prescription formulation specifically designed for treating head lice. This brand has been available for many years and is the version most doctors prescribe when recommending malathion treatment.

Generic versions of malathion lotion are also available, but they contain the same active ingredient and work in the same way as the brand-name version. Your pharmacy might carry either the brand name or generic version depending on availability and your insurance coverage.

Malathion Alternatives

If malathion isn't suitable for you or hasn't been effective, several alternative treatments can help eliminate head lice. Over-the-counter options include permethrin-based treatments like Nix and pyrethrin-based products like RID. These medications work differently from malathion but are often effective for many people.

For cases where traditional treatments haven't worked, your doctor might recommend newer prescription options. Benzyl alcohol lotion (Ulesfia) works by suffocating lice, while ivermectin lotion (Sklice) targets the lice nervous system through a different mechanism than malathion. Spinosad suspension (Natroba) is another option that's particularly effective against resistant lice.

Non-chemical alternatives include wet combing with a fine-toothed lice comb, which can be effective when done thoroughly and repeatedly. Some people also try natural remedies like tea tree oil or coconut oil, though these haven't been proven as effective as prescription treatments.

Is Malathion Better Than Permethrin?

Malathion and permethrin work through different mechanisms, making each more effective in certain situations. Permethrin is often the first-line treatment because it's available over-the-counter and has fewer restrictions on use. However, malathion tends to be more effective against lice that have developed resistance to permethrin-based treatments.

Studies suggest that malathion has a higher success rate overall, particularly in areas where lice resistance is common. The medication's dual action of disrupting the nervous system and suffocating lice makes it harder for parasites to survive. However, malathion requires more careful application and has more safety precautions than permethrin.

Your doctor will typically recommend starting with permethrin for most lice infestations, reserving malathion for cases where other treatments have failed or when dealing with known resistant lice. The choice between these medications depends on your specific situation, medical history, and local patterns of lice resistance.