text: how soon do you contract food poisoning? in conjunction with another question i posted, how long does it take before food poisoning is in your system? when you feel the effects? i've had it before but just wondered. depends on the type of food poisoning. there is  food intoxication that can see symptoms set in within 3 hours. this would a violent type of illness with vomitting and other symptons setting in similar to getting really drunk very fast.   there is also food infection that can see symptons set in  within 8 hours. symptoms can be gradual similar to a flu.  the only really effective manner in which to determine whether you have had fodd poisoning is to have the doctor test a stool sample.  lots of great info at: http://www.nlm.nih.gov/medlineplus/ency/article/001652.htm#symptoms