The head lice being found today in schools are becoming resistant to the poisons found in most commercial head lice products. So not only does using them expose the child to dangerous toxins, the treatment frequently doesn't work. This is extremely frustrating for the parent trying to rid the child and the house of head lice. There are several alternative treatments, mayonnaise being one of them.
Applying mayonnaise, olive oil or crisco to the hair is a popular method of killing off head lice. I have seen nits survive this treatment, however. It is almost impossible to completely cover every inch of the hair and scalp thickly enough to smother the nits and lice. It's important to follow this treatment with a careful, time consuming session or two with the nit comb. This is an extremely fine toothed comb that is designed to comb the nits off of the hair shaft. This isnt 100% effective either, though. The best method of removing nits, in my opinion, is by sitting with the child and carefully and completly examining every portion of the childs hair and manually picking the nits off with your fingernails. A follow up shampoo with tea tree oil either added to the shampoo or applied to the hair makes you that much more sure that all the critters are dead. As a final precaution, blow dry the hair on the hottest setting.
The house, clothing, car seats, stuffed animals, hats, and any other item the child's hair might have come in contact with have to be treated as well. Heat is one way to kill lice and nits. The easiest and best way though is to just go somewhere else for 3 days. If there is no human host for 3 days, all of the nits and lice found in the house, clothing, and car will die off. Go camping, check into a motel, visit grandma and grandpa. Starve those lice, and you don't have to worry about missing killing any of them. Time will take care of it.