How long does it take for allergy medication to work?

Key takeaways

• Most oral antihistamines start working within 30 minutes to 1 hour by blocking histamine, the compound that triggers inflammation and allergy symptoms like sneezing, itching, and congestion.
• Second-generation antihistamines like fexofenadine (Allegra), loratadine (Claritin), and cetirizine (Zyrtec) are often favored by healthcare professionals because they manage symptoms more effectively and are less likely to cause drowsiness than first-generation options.
• For best results, take allergy medications 2 to 4 weeks before your allergy season begins to build full protection. If you have severe or recurring symptoms, talk with a healthcare professional about allergy testing or immunotherapy options.

Overview

Antihistamines are the most common medication for treating allergies. They help ease symptoms such as sneezing, itching, and congestion.

They work by blocking the histamine compound that your body releases as it encounters an allergen. Histamine is responsible for regulating inflammation, which causes your immune response to activate.  

Allergens are substances that trigger an allergic reaction. They can include anything from pollen and dust mites to certain substances in foods.

All allergy medications start to work fast, but timing will vary slightly depending on the type you take. These types include nondrowsy and drowsy medications.

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When is the best time to take allergy medications?

Allergy medications work well as preventive measures to stop your allergy symptoms from developing. If you know what causes your allergies, it is much easier to use allergy medications effectively.

According to the Allergy and Asthma Network, you should aim to take your allergy medications anywhere between 2 and 4 weeks before the start of your allergy season. This allows you to gain full protection by the time the season begins.

If a doctor prescribes you antihistamines, take your medication as the doctor advises.

It’s important to remember that antihistamine medications do not cure your allergies but help to relieve your symptoms.

How long do antihistamines take to work?

Most oral antihistamine allergy tablets work fast — on average, in just 30 minutes to 1 hour. This will vary slightly between specific medications.

Other medication types, like eye drops and nasal sprays, may take different amounts of time to work.

You should always check the packaging of your allergy medications to know when to expect symptom relief.

What are the different types of allergy meds?

There is a wide range of antihistamine medications available.

First generation

First-generation oral antihistamine tablets include:

• diphenhydramine (Benadryl)
• dimenhydrinate (Dramamine)
• promethazine (Phenergan)

These medications easily cross your blood-brain barrier to help prevent the inflammation that causes allergy symptoms. They affect H1 receptors in your central nervous system (CNS), which helps regulate your sleep cycle, meaning that first-generation antihistamines can make you drowsy and affect your motor functions.

If you choose first-generation antihistamines, it is best to take them at night to avoid these drowsy effects.

Second and third generation

Newer antihistamines are nondrowsy because they are less likely to cross the blood-brain barrier. This means they are much less likely to cause any side effects on your CNS.

Second-generation antihistamines more effectively manage allergy symptoms than first-generation medications and cause fewer side effects.

According to 2019 research, almost 73% of family doctors prescribe second-generation antihistamines rather than first-generation options for allergic disorders.

Second-generation antihistamines include:

• fexofenadine (Allegra)
• loratadine (Claritin)
• cetirizine (Zyrtec)

Over-the-counter (OTC) and prescription medications

Both first- and second-generation antihistamines are available at your local drugstores and pharmacies. You can purchase them in different forms, such as sprays, oral tablets, or eye drops, and they are suitable for mild to moderate allergies.

Prescription antihistamines are stronger, so if you have severe allergy symptoms, speak with a doctor, as they may prescribe antihistamines that could include:

• desloratadine (Clarinex)
• carbinoxamine (Arbinoxa)
• hydroxyzine (Atarax)
• azelastine nasal sprays (AstePro)

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Allergy immunotherapy

Allergy shots, or immunotherapy, use tiny doses of allergens to help you build immunity and reduce your symptoms.

According to the American Academy of Allergy, Asthma, and Immunology (AAAAI), this therapy is split into two phases:

• Buildup phase: This involves receiving injections with increasing amounts of the allergen, about 1 to 2 times per week. The length of this phase depends on how often the injections are received, but generally ranges from three to six months.
• Maintenance phase: Once you reach the most effective dose, there will be longer periods of time between treatments, ranging from two to four weeks. This phase may last up to 12 months.

You may also receive sublingual immunotherapy. This type of immunotherapy avoids injections and uses oral tablets that dissolve under your tongue, but it is only currently available for dust mite, ragweed, and grass pollen allergies.

Allergy testing and contacting a doctor

If you experience regular or severe allergy symptoms, a doctor may recommend an allergy test.

This may include:

• A skin prick test: A doctor places small amounts of different possible allergens on your skin to see whether a reaction occurs.
• Blood tests: Your blood sample is sent to a lab to check for allergy markers.
• A diet review: A doctor recommends that you avoid certain foods to see whether your symptoms improve.

This generally requires an in-person appointment. However, you may be able to be evaluated for allergy treatments online.

Online care services, including Optum Perks Online Care, may make getting treatment easier. With these services, you can submit an online form answering a few questions about your symptoms, and a US-licensed healthcare professional will respond soon after to prescribe a treatment plan.

Summary

Antihistamine medications take an average of 30 to 60 minutes to start working. Depending on how you take the medication, this can vary.

Doctors often recommend second-generation antihistamines over first-generation, as they are more effective and less likely to cause side effects like drowsiness. There is a wide variety of both types available OTC and by prescription.

If your allergy symptoms are severe, allergy testing and long-term immunotherapy can help reduce your symptoms.

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Disclaimer: While Optum Perks strives for factual, comprehensive, and current information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses.