A woman in Denmark spent time in hospital after using garlic as a herbal remedy. Two days previously she had applied 15 slices of fresh garlic to her knee in an attempt to relieve chronic pain. Cling film was applied on top and the leg was bound with a scarf. Despite a stinging, burning sensation, the woman kept the garlic poultice on for three hours.

 Even though doctors waited several weeks in the hope that the "garlic burns" would heal naturally, they were finally forced to operate and do a skin graft on the affected knee.

 According to Dr Kirsten Hviid, "It is the first time in the world that anyone has seen a garlic burn that was so bad it needed a skin graft."

 Doctors have known since 1952 that garlic can cause burns. It can be either an allergic reaction, or as a toxin, as the juices from the garlic eat into the skin. There are only seven previously recorded cases of garlic burns worldwide.

 "There is a theory about what the chemical reaction is, but it is not totally defined yet. It could be interesting to find out just what there is in garlic that is so potent that it can cause second degree burns," said Kirsten Hviid.

By Penny Leese, just-food.com correspondent