Your skin can become very swollen and irritated from allergies," says Debra Jaliman, M.D., a dermatologist in New York City and the author of Skin Rules: Trade Secrets from a Top New York Dermatologist. This is due to seepage of serum (a clear fluid in the blood that triggers allergic reactions) into the skin. Jaliman recommends anti-inflammatory antihistamines to reduce swelling (look for Allegra or Zyrtec, both of which are available OTC, if you're a first-time allergy sufferer). You can also place ice packs directly on the under-eye area for relief.