The US Centres for Disease Control and Prevention (CDC) says that hand sanitisers should contain at least 60 per cent ethyl alcohol or 70 per cent isopropyl alcohol. Other approved ingredients may include sterile distilled water, hydrogen peroxide and glycerine, according to experts at the US Food and Drug Administration (FDA).

You should also avoid anything with methanol or 1-propanol, as both these chemicals can be highly toxic. The FDA has also warned people to watch out for hand sanitisers packaged in food and drink containers, since accidentally ingesting them could be dangerous.

Health officials have advised to avoid hand sanitisers that replace alcohol with benzalkonium chloride, since its less effective at killing certain bacteria and viruses. Making your own sanitiser isn't encouraged either, because accidentally mixing the wrong chemicals can make it ineffective or even cause skin burns.

And you should only use a hand sanitiser when you cannot wash your hands with soap and water, says Barun Mathema, an infectious disease researcher at Columbia University.