Tea tree oil has been promoted as a treatment for head lice; however, there is disagreement on its effectiveness.[20][21][22] A 2012 review of head lice treatment recommended against the use of tea tree oil for children because it could cause skin irritation or allergic reactions, because of contraindications, and because of a lack of knowledge about the oil's safety and effectiveness.[23] Other home remedies, such as putting vinegar, isopropyl alcohol, olive oil, mayonnaise, or melted butter under a shower cap, have been disproven.[9] The CDC states that swimming has no effect on lice, and can decrease the effectiveness of some treatments.[24]