Antihistamine or a Decongestant?

By Stephanie Watson and Temma Ehrenfeld @temmaehrenfeld
December 04, 2023
Antihistamine or a Decongestant?

Here’s how to tell whether an antihistamine or a decongestant will help your cold or flu symptoms — and when you should avoid these medicines entirely.

When a cold plugs your nose and turns it into a leaky faucet, one way to release the clog and stop the drip is to take an over-the-counter antihistamine or decongestant. But be careful when using these drugs because they’re not right for everyone, and they can have side effects — some potentially serious — when used incorrectly.


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During an infection or allergy attack, your body releases a chemical called histamine. Antihistamines block the action of this chemical, which can trigger a runny nose, watery eyes, and sneezing.

Some antihistamines have been around for many years.

First-generation drugs include diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton), and brompheniramine (Dimetane).

Newer-generation antihistamines include fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec), and levocetirizine (Xyzal).

Older antihistamines tend to cause drowsiness, which can be a problem if you need to drive a car, operate heavy machinery, or stay awake through a work or school day. In that case, take a newer antihistamine or save the older one for bedtime to help you sleep. 

Know that the research on whether antihistamines help colds in adults is mixed, at best. If one helps, it will probably work for only the first day or two.  


Swollen blood vessels inside your nose cause congestion. Decongestants shrink those engorged blood vessels to help you breathe easier. They usually include the ingredients pseudoephedrine or phenylephrine marketed as Drixoral, Dimetapp, Afrin, and Sudafed. Decongestants are available in pill, liquid, or spray forms.

While helping you breathe easier, decongestants can also make you feel jittery and boost your blood pressure. Decongestant-free cold relievers like Coricidin HBP are safer for people with high blood pressure.

If you take a traditional decongestant, monitor your blood pressure to make sure it stays within the range your doctor recommends. Blood pressure numbers less than 120/80 are normal.

“If it increases excessively and is consistently over 140/90, then they need to speak to their doctor,” says Willie E. Lawrence, Jr., MD, a cardiologist in Kansas City.

Spray decongestants can become habit-forming, and they’re not recommended for more than three days. With more than three days of use, you can develop rebound congestion, putting you right back where you started.

Combo products

Some products combine an antihistamine and decongestant in one pill. Brand names include Chlor-Trimeton D, Claritin-D, Dimetapp, Drixoral, Sudafed Plus, and Tavist-D. Taking the two drugs together may help balance out the jitteriness and sleepiness they can cause individually.

Multi-symptom cold medicines contain a decongestant or antihistamine, plus ingredients to combat other cold symptoms, such as a pain reliever and cough suppressant. Though these drugs relieve multiple symptoms at once, you could end up getting medicine for symptoms you don’t have.

You’re better off using an individual decongestant or antihistamine if congestion, runny nose, and sneezing are your main symptoms. 

Homeopathic remedies

At your pharmacy and online, you may see other cough and cold medicine advertised as homeopathic. They might say they are natural and look like vitamins, but that doesn’t mean they’re harmless. No homeopathic remedy has met the standards of the Food and Drug Administration (FDA) for safety and effectiveness.

As the agency notes, “Homeopathic products are generally labeled as containing very small amounts of highly diluted substances, including ingredients from plants, animal or human sources, bacteria, minerals, and chemicals. The FDA has found that some of these products contain active drug ingredients in levels that far exceed the amount stated on the product’s label.”

Cold medicines and kids

Antihistamines and decongestants are not recommended for children; they can cause serious side effects in this age group.  

“Although scientific evidence does not support the use of cold medicines in children, unintentional intoxications by these drugs keep happening, in some cases causing moderate or severe symptoms,” note the authors of a study documenting 31 cases of children who were seen in an emergency room because of a reaction to decongestants.

Because many of these drugs look like candy, keep them well out of children’s reach. Many children visit emergency rooms each year after taking cold and cough medicines — most of them without a parent’s knowledge. 

Children have been hospitalized because of reactions to homeopathic cold remedies as well.


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December 04, 2023

Reviewed By:  

Janet O’Dell, RN