How long do allergy shots take to work?

Some people feel a little better during the 3-6 month build-up phase, but meaningful improvement usually comes on the maintenance dose. Expect the first year to be the realistic window: it can take up to 12 months on maintenance to notice a clear reduction in symptoms.

Allergy shots gradually retrain your immune system to tolerate the allergen instead of overreacting to it. That immune change takes months to develop, which is why relief builds slowly. In exchange, the benefit tends to last for years, unlike antihistamines that only work while the medicine is active.

If allergy shots are helping, maintenance treatment is typically continued for three to five years, sometimes longer. Completing the full course is what produces lasting benefit, and many people continue to experience relief for years after their treatment ends. Your allergist decides when it is reasonable to stop.

Sublingual immunotherapy (allergy drops) follows a similar gradual timeline to shots, with partial improvement sometimes noticed within months but the meaningful, durable benefit building over a multi-year course. The main difference is the route: drops are taken at home without needles, but both are long-term treatments rather than quick fixes.

After completing a full three-to-five-year maintenance course, many people continue to experience reduced allergy symptoms for years afterward, since the treatment works by retraining the immune system rather than just masking symptoms temporarily. Benefit duration varies by person and by how complete the treatment course was. Stopping early, before maintenance is finished, raises the chance that the improvement fades sooner. Your allergist can help you judge when you have reached a stable, lasting result.

Oral antihistamines such as Allegra, Zyrtec, or Claritin typically begin relieving symptoms within one to three hours of a dose, and the full effect often builds over a day or two of regular use. This is much faster than allergy shots or drops because antihistamines simply block the histamine reaction in the moment rather than changing the immune system. The trade-off is that relief only lasts while the medication is active, and it does nothing to reduce your underlying sensitivity the way immunotherapy does over time.

Xolair (omalizumab) works differently from allergy shots — it is an injectable biologic that blocks IgE antibodies rather than retraining immune tolerance. Most people need several months of regular dosing, often in the range of 12 to 16 weeks, before noticing a meaningful drop in allergic or asthma symptoms. It is prescribed and monitored by a physician, and the exact timeline varies by individual and by the condition being treated.

Curex is a telehealth platform, not a drug, so this depends on which treatment you mean. Allergy shots use FDA-regulated extracts, and SLIT tablets for a single allergen go through full FDA drug approval. Compounded, multi-allergen liquid allergy drops are prepared by a licensed pharmacy under your prescribing clinician's order, similar to other individualized compounded medications your doctor can prescribe. Ask your care team if you want the regulatory details for the specific treatment you are considering.

Allergy shots themselves are not sedating — unlike older antihistamines, the injection does not contain anything that causes drowsiness. Some people feel briefly tired or achy at the injection site, similar to a mild reaction to any vaccine, and rare systemic reactions can include symptoms beyond sleepiness that should be reported to your provider right away. If you feel unusually drowsy after a shot, mention it to your allergist so they can check whether another medication you are taking is the real cause.

The main alternatives are sublingual allergy drops or tablets (SLIT), which work on a similar immune-retraining timeline without needles, and daily or as-needed antihistamines, nasal sprays, or eye drops, which manage symptoms quickly but temporarily and don't change the underlying allergy. For some people, allergen avoidance strategies, like reducing dust mite or pet exposure at home, also help. An allergist can help you weigh shots, drops, and medication based on your specific allergens, lifestyle, and how much relief you need.