How long does it take for symptoms of food poisoning to start? would i know within 5 hours?

Not always: Food poisoning refers to consuming foods that are contaminated with bacteria. Sometimes the symptoms of nausea, vomiting and diarrhea start within a few hours, but sometimes it takes several days for the bacteria to multiply before giving symptoms. A good reference is the following: Food poisoning Symptoms - Mayo Clinic www.mayoclinic.org/.../food-poisoning/.../symptoms/con-20...

Variable: There are different types of food poisoning - some are caused by viral illness, some by bacteria, and others from exotoxins produced by bacteria. Symptoms such as nausea, vomiting, stomach cramping and diarrhea may occur within minutes to a day or two.