My DS2, now almost 3, had febrile seizures at 17 months. You're right, it's SCARY. Forgive me for the length of this...
He had a 102 temp the night before (brought down by Tylenol), another temp at 8:30 a.m. (brought down by Tylenol), and just after noon he had a series of seizures.
DH, who's a stay-at-home dad, and our boys were in a parking lot preparing to go home. DS2 was strapped into his car seat, DH was strapping in DH1 (then almost 3), when he looked across and saw DS2 look like he was choking. He got him out and realized it wasn't choking. Nice man in the parking lot lent his cell phone, they called 911 to get an ambulance, then called me at work. (I had been expecting a call about my dad, who was having heart surgery to have 2 stents put in; dad and DH2 ended up in the same hospital.)
When I got to the ER DS2 was naked in DH's arms, shrieking, and bucking to get away. He had an IV in. I asked them if I could lay on the patient bed, and started breastfeeding DS2 immediately. He calmed down and I got him to sleep. His fever was just over 105.
BTW, I learned later that it's not how high the temp goes, but rather how FAST it increases that causes seizures. They can have seizures at 101 if the temp increases too fast.
The ER folk used him for a pincushion: IV, catheter (for a urine sample), heal-stick for blood (which they shouldn't have done since he was already walking), lumbar puncture, and two thigh-shots (to administer a broad anti-biotic). Include several rectal thermometer checks, and you get the idea -- every time he fell asleep they wanted to poke him again.
Once they ruled out meningitis or any other scary disease, and after they brought his temp down, they discharged us. Other than the pincushion thing they were nice -- they fed me (since I was feeding him <grin>) and they gave him a nice stuffed animal. They prescribed BOTH ibuprofen (every 6 hours) AND Tylenol (every 4 hours) for the next several days -- we weren't allowed to give his body the SLIGHTEST chance that it would get even a little warm.
They also told us to schedule an EEG (brain scan), which we did. Since this is already so long, please PM me if you want to get the scoop on the EEG (which is a whole 'nother Oprah). We were told that the reason they wanted the EEG was because he had "complex seizures": a seizure, then awake, then a seizure, then awake, etc. If it had been only one they wouldn't have recommended it.
There have been NO long-term effects (except for our nervousness every time he gets a temperature, I mean). And the EEG showed nothing out of the ordinary. We like to tell people that we have PROOF that he has a brain, lol. The longer he goes without seizures the less likely it is that he'll have another one.
And, BTW, my father is fine, too.