Alcohols such as vodka combined with other ingredients are an effective, non-toxic alternative way to kill head lice, according to Sustainable Baby Steps. LiceWorld.com notes that head lice have gained tolerance toward some alcohols.
Sustainable Baby Steps advises that vodka can be mixed with tea tree oil as a treatment for head lice. It should be left in hair for at least 12 hours before washing with shampoo. This treatment can be reapplied frequently as a preventive measure, the site adds.
LiceWorld.com states that while head lice have built tolerance to some alcohols, those with a greater molecular size still show activity against the pests as of 2014. Some of these alcohols can irritate human skin.