Im seeing a dentist tom, havent been there before, a neighbor said i shouldnt take anything like painkillers cause you never know what they'll need to use, is she right, and also, is it okay to eat before i go, is it okay to take claritin before?

The initial visit would be mostly for diagnosis and may not involve any treatment as the dentist will inspect the area, get X-rays and come up with a treatment plan once a cause is found. Having previous dental records transferred will help and you should be taking pain meds as instructed with no other restrictions. Eating and using claritine prior to visit would be fine.

Not sure what your visit is for, but taking analgesics before the visit may mask a problem that is present. Eating and taking claritin should be fine.