Do you know what a febrile convulsion is? When we speak to parents about these, we are often met with a "what's that!?". However, with as many as one in 30 children having these as a result of fever, we want to take the time to make sure YOU know what they're all about. A febrile convulsion is a fit or seizure caused by a sudden change in your child's body temperature and is usually associated with a fever. Febrile convulsions can be upsetting to witness, but they are not harmful to your child.