Over-the-counter medications such as A-200 and Pronto contain pyrethrin, a natural insecticide that works by interfering with the nervous system of lice and killing them, explains Health.com. To remove the nits, it is necessary to apply the medication on the dry scalp, allow at least 10 minutes before lathering with water and rinsing, and comb to remove the nits. Experts recommend a second application within seven days to eliminate any remaining lice.
Spinosad, a prescription lotion containing a natural insecticide developed using bacteria found in the soil, provides relief from head lice, states Health.com. The product is safe for use in children four years of age and older. In two separate trials to determine its effectiveness, spinosad killed all head lice within 14 days in 84.6 percent and 86.7 percent of patients.
Applying a smothering agent such as petroleum jelly or olive oil on the scalp cuts off the air supply to nits and lice, which suffocates them, notes Mayo Clinic. An affected person must cover the hair with a shower cap for several hours to kill all the critters and repeat the process after a few days, for better results. Studies indicate that some natural oils, such as tea tree oil and anise oil, are toxic to lice and their eggs. Prescription treatments provide relief when over-the-counter medications are ineffective. Some of these treatments include benzyl alcohol, which suffocates lice and is approved for use in children older than six months.