The CDC recommends using repellants that contain active ingredients registered with the EPA. EPA registration means that the EPA does not expect the product to cause adverse effects to human health or the environment when used according to the label.
Of the products registered with the EPA, those containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, and 2-undecanone products provide longer-lasting protection.
Products containing all-natural ingredients, such as peppermint, thyme, eucalyptus, and garlic, do not require EPA registration and have not been evaluated by the EPA for their effectiveness as mosquito repellents.