Doctors yesterday urged Hongkongers to learn the first signs of a severe allergic reaction to food, after news from Canada that a 15-year-old girl with a peanut allergy died after kissing her boyfriend, who had eaten a peanut butter snack. Georges Halpern, distinguished professor of pharmaceutical sciences at Hong Kong Polytechnic University, said the Canadian case was 'very exceptional' but a similar case could happen here. 'Even people who are severely allergic to peanuts need more than saliva contaminated with microscopic parts of peanuts to go into anaphylactic shock. This young lady was probably tremendously allergic,' Professor Halpern said. 'But it is a risk that is real and as shown by this Canadian case, it can happen.' Ellis Hon Kam-lun, an associate professor in paediatrics at the Chinese University, agreed. 'It is important to educate relatives, and friends if a person has a severe allergy so that they know what to do when such an incident happens.' 'The onset will be fast - a bit of choking, coughing, a sensation of discomfort in the tummy or a rash on the body.' The symptoms can include hives and swelling of the face and throat, which can block breathing. Patients suffering from severe allergic reactions should be taken immediately 'to any doctor' as clinics would have the necessary stock of adrenaline or epinephrine. Professor Hon said an emergency treatment called Epipen could be prescribed for people with 'genuine severe allergies', which they could carry with them. Epipen is an adrenaline injection that is fast-acting and simple to use. Even children as young as four can be trained to use it. Unlike seafood and milk allergies, which children usually outgrow, a peanut allergy is generally for life. Peanut allergies have been rising in recent decades. The reason remains unclear, but one study found that baby creams or lotions with peanut oil may cause children to develop allergies. Peanut allergies afflict less than 1.5 per cent of Asians.