Allergy Relief: Antihistamines vs. Decongestants

Medically Reviewed by Jabeen Begum, MD on April 18, 2024
Written by Lori M. King, PhD
5 min read

The two most common types of allergy medications are antihistamines and decongestants. Antihistamines and decongestants don't cure your allergies, but they’ll give you much-needed relief for a runny or congested nose. They're available both as a prescription and over the counter (OTC) in several forms:

  • Eye drops
  • Nasal sprays
  • Inhalers
  • Pills
  • Liquids
  • Skin creams
  • Shots (injections)

Histamine is a chemical your immune system makes. It does a few things, such as regulating your sleep cycle. But it also helps send signals between cells, which is part of why you have allergy symptoms. Antihistamines are medicines that block histamine from binding to your cells, which can make your symptoms better.

Antihistamines come in several forms, such as pills, liquids, nasal sprays, or eye drops. Pills target itching, sneezing, and runny nose. Nasal sprays work on congestion, an itchy or runny nose, and postnasal drip.

Antihistamines can ease your symptoms, but they work best when you take them before you feel a reaction. They can build up in your blood to protect against allergens and block the release of histamines. Ask your doctor if you should start taking allergy medicine a couple of weeks before you usually have symptoms.

Some common antihistamines you can get OTC as pills or liquids are:

  • Cetirizine (Zyrtec)
  • Chlorpheniramine (Chlor-Trimeton)
  • Clemastine (Tavist)
  • Desloratadine (Clarinex)
  • Diphenhydramine (Benadryl)
  • Fexofenadine (Allegra)
  • Loratadine (Claritin)

Antihistamine eye drops

These can help ease itchy eyes and problems with your nose. You can try:

  • Azelastine (Optivar)
  • Ketotifen (Zaditor)
  • Naphazoline (Opcon-A, Visine-A)
  • Olopatadine (Patanol)

Antihistamines are classified as first- or second-generation. First-generation antihistamines can easily cross over from your bloodstream to your brain, so they can make you feel very sleepy. On the other hand, second-generation antihistamines don't tend to cross over into your brain as easily, so they don't make you feel as sleepy.

Examples of first-generation antihistamines include:

  • Chlorpheniramine (Chlor-Trimeton)
  • Clemastine (Tavist)
  • Diphenhydramine (Benadryl)

Examples of second-generation antihistamines include:

  • Cetirizine (Zyrtec)
  • Desloratadine (Clarinex)
  • Fexofenadine (Allegra)
  • Loratadine (Claritin)

Decongestants work by reducing the swelling in the blood vessels in your nose. This relieves your blocked and stuffy nose and helps open your airways.

Decongestants are available in various forms, such as nasal sprays, eye drops, tablets, capsules, liquids, and powders.

Decongestants aren't recommended for people with high blood pressure, heart disease, glaucoma, or hyperthyroidism.

Examples of common decongestants you can get OTC as tablets or capsules include:

  • Phenylephrine (Sudafed PE)
  • Pseudoephedrine (Sudafed)

Some medications combine decongestants with other medicines, such as pain relievers and/or antihistamines.

Examples of these include:

  • Pseudoephedrine and cetirizine (Zyrtec-D)
  • Pseudoephedrine, guaifenesin, and acetaminophen (Tylenol Sinus Severe Congestion Daytime)
  • Pseudoephedrine and ibuprofen (Advil Cold and Sinus)
  • Pseudoephedrine and loratadine (Claritin-D)

Decongestant nasal sprays

These work faster than tablets or capsules. Examples include:

  • Oxymetazoline (Afrin, Zicam)
  • Phenylephrine hydrochloride (Neo-Synephrine)
  • Tetrahydrozoline (Tyzine)
  • Xylometazoline (Otrivin)

Don't use nasal sprays for more than a few days in a row because they can worsen your swelling and stuffiness. This is called a "rebound reaction." You get temporary relief, but your symptoms come back worse than before. So, if you use nasal decongestant sprays, limit it to a maximum of 3 days.

Corticosteriods (or steroids) are a powerful way to fight stuffiness, as they get to the root of the problem by directly reducing your swelling. They can be especially helpful, for instance, if you have seasonal allergies and you know you're going to be stuffy until the season changes.

These also come in several forms, including sprays, inhalers, eye drops, pills, liquids, and creams.

Steroid nasal sprays

Nasal steroids are a type of nose spray and are often the first drugs recommended for allergies.

They lessen your whole allergic inflammatory process. Plus they target all your allergy symptoms, not just congestion.

You can get these OTC:

  • Budesonide (Rhinocort)
  • Fluticasone (Flonase)
  • Mometasone (Nasonex)
  • Triamcinolone (Nasacort)

If you decide to use one, be patient. You don't get the full effect for several days or even a week. But if you use it daily, it can be very effective. You can also use steroids together with antihistamines or decongestants to get extra relief. Or, use an antihistamine or decongestant for short-term relief while you wait for your steroids to work.

Allergy shots (allergen immunotherapy) 

You may want to consider them if you have allergy congestion all year and medication doesn't help much. It gets your body used to the things that trigger your hay fever so you won't have an allergic reaction.

Allergy shots can be very effective, but they don't work quickly. You get a series of injections over several years. Each one has a small dose of the stuff that causes your allergies.

Some allergists are turning to another form of immunotherapy, called sublingual immunotherapy (SLIT), which doesn't use injections. You may be able to take a pill that dissolves after you put it under your tongue. Examples are Grastek, Oralair, and Ragwitek. You need to take the first one at a doctor's office, but after that, you can use them at home.

Mast cell stabilizers

Mast cells are a type of immune system cell. They release chemicals that can cause your allergy symptoms. Mast cell stabilizers keep these cells from releasing their chemicals. Your doctor may prescribe these for you when antihistamines don't work for you or if you have intolerable side effects. You usually need to use these for a few days before they take full effect.

They come as nasal sprays, such as cromolyn sodium (NasalCrom), and eye drops, such as:

  • Cromolyn (Crolom)
  • Lodoxamide (Alomide)
  • Nedocromil (Alocril)

Leukotriene inhibitors

Leukotrienes are other chemicals that your immune system releases, causing symptoms. Leukotriene inhibitors block these chemicals from binding to your cells. This eases congestion, runny nose, and sneezing. Only one type is available for hay fever: montelukast (Singulair).

Emergency epinephrine shots

These are used for people with anaphylaxis, which is a potentially life-threatening allergic reaction. Your doctor can prescribe it for you. If you have serious allergies, you should keep at least two of these with you at all times. They come as auto-injecting syringes.

Some of these drugs need a prescription. Others don't. First, try an OTC brand. But check with your doctor or pharmacist to make sure you have the right medication for your symptoms. If you don't get relief, ask for something stronger.

Check drug labels for more information about side effects.

Antihistamines side effects

You shouldn’t drive when you take antihistamines , especially first-generation antihistamines, as they can make you drowsy. These include brompheniramine (Nasahist B), chlorpheniramine (Chlor-Trimeton), clemastine (Dayhist, Tavist), and diphenhydramine (Benadryl). Second-generation antihistamines usually don’t make you drowsy. Examples include desloratadine (Clarinex), fexofenadine (Allegra), and loratadine (Alavert, Claritin).

Decongestants side effects

Decongestants can also cause side effects, such as:

  • Nervousness
  • Sleeplessness
  • Increased heart rate
  • Increased blood pressure

You shouldn’t take decongestants if you have certain health issues, including high blood pressure or heart problems. If you have prostate problems that make it hard to pee, these drugs can make the problem worse.

Antihistamines and decongestants are the two most commonly used types of allergy medications. They don't cure your allergies, but they can make your symptoms go away for a while. You can even combine them (or buy a combination medication) if you don't get relief from one or the other.