Esomeprazole, the acid-reducing part of this medicine, does not cause any clinically significant interaction with terfenadine when given to healthy people. Terfenadine is one of several drugs the body breaks down through the cytochrome P450 system, and studies have found that esomeprazole does not meaningfully change how it works in that case, so the two can be taken without any major concern for healthy adults.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.