Any alternatives to oral antihistamines?

Depends: It depends on what symptoms you are treating. Assuming that you are treating seasonal allergy symptoms, you could also try prescription nasal sprays, singulair, (montelukast) or allergy shots.

Several: For treating allergies, avoidance is important if practical/possible. Antihistamines are also available as a nasal spray. The most effective treatment for nasal allergies are the nasal steroid sprays. Leukotriene modifier (like singulair (montelukast) pills) is an option. Long term control is best achieved through treatment with allergy injections.