Also, the more you use the drug, the less effective they get over time. If your allergies are persistent, ask your doctor for a nonsedating antihistamine like Allegra, Claritin, or Zyrtec. Other alternatives include a nasal steroid spray such as Flonase or Nasonex. But these take 3 to 10 days to kick in, so you need to start before symptoms get out of control. Allergy shots raise your body's tolerance to allergens.
Research suggests the shots have long-term, perhaps even permanent, benefits.