Allergy medicines generally start working within 30 minutes to 2 hours after taking them, depending on the type. Fast-acting options like oral antihistamines (e.g., Zyrtec, Claritin), antihistamine nasal sprays, and decongestants provide quick relief, often within minutes to an hour. Nasal sprays may take a few days for full effect, and long-term treatments like allergy shots or immunotherapy take several months to years for full effectiveness. Taking medication before symptoms start can improve how well and quickly it works.
Allergy Medicine Onset Times
- Oral antihistamines: 30 minutes to 2 hours
- Antihistamine nasal sprays: 15 to 30 minutes
- Antihistamine eye drops: Within minutes
- Nasal steroid sprays: A few days of consistent use
- Allergy shots/immunotherapy: Initial improvement in 3-6 months, full effect in 1-3 years
Tips for Best Results
- Begin medication before allergy season or exposure
- Take medicine consistently as directed
- Consult an allergist if symptoms persist despite treatment
In short, for most common allergy medicines, noticeable relief is felt within an hour or two, but some require consistent use over days or months for full benefit.
