What is the best method to diagnose gerd?

See your doctor: or a gastrointestinal specialist. If your symptoms are consistent with GERD, the doctor might prescribe a medication such as Pepcid (famotidine) or other as a trial, which would be both for treatment and diagnosis (if it works, that may be the diagnosis). Other testing, done by the specialist could include an endoscopy to look directly at the esophagus and stomach and possibly take a specimen to test.