Elizabeth Perkins, a 30-year-old woman living in Swadlincote, Derbyshire, saw her life flash before her eyes when she drank a single sip of diet soda. Indeed, the mother of two children suffers from a rare allergy to synthetic sweeteners found in many 'light' drinks.While she was in a bar, Perkins asked the waiter for a classic soda and not a light one. She only took one sip, saying afterwards: 'Once I took my first sip I immediately felt a strange taste and started to feel the usual effects coming on.'Her allergy to aspartame, an artificial sweetener, caused her to go into a coma for three days. 'I immediately felt dizzy and the room went dark. I later learned that a friend put me back in my chair, but I had already fainted,' said the patient.A potentially fatal allergyElizabeth Perkins says she made it clear to the bartender that she needed a normal soda, and not a light one, but 'the problem is that most people don't see the difference.' Yet, for this mother of two children, who probably suffer from the same allergies as their progenitor, this difference may well be a matter of life or death.The English woman explained to the Daily Mail that her body does not have the enzymes necessary to digest artificial sugars. This is why they act as a poison in the patient's body, who may vomit and feel dizzy if she consumes them. Fortunately, Elizabeth Perkins is now out of the woods.