Links to other useful web sites
nhschoices - www.nhs.uk/Conditions/Head-lice/Pages/Introduction.aspx : - information about head lice, symptons, diagnosis, treatment and prevention.
netdoctor - www.netdoctor.co.uk/diseases/facts/lice.htm: - includes useful information on pros and cons of different treatments on the market.
about.com paediatrics - http://pediatrics.about.com/od/headlice/a/0906_lice_prev.htm Includes information on do's and dont's to help prevent head lice
Mayo Clinic - www.mayoclinic.com/health/hea-lice-prevention/AN02174 - details concerns that studies have shown that ingredients in some of the over-the-counter products - mostly plant oils such as rosemary, citronella, eucalyptus, tea tree and lemon grass - are classified as "natural" so they aren't regulated under the Biocide Regulations or MHRA (Medicines and Healthcare Products Regulatory Agency) in the EU or Food and Drug Adminsitration (FDA) or the Environmental Protection Agency (EPA) in the USA. As a result their safety and effectiveness haven't been tested to meet regultory standards.
As a general rule it is unwise to purchase any product over the internet which is not from a reputable supplier as you may never know what is actually in the product!