It’s normal to be tired at the end of a long day — but when Greta Schulz’s allergies are acting up, fatigue is more of a rule than an exception.

“I drink two coffees every morning and Diet Coke all day to stay awake,” says Schulz, the CEO of a training and consulting firm in West Palm Beach, Fla. “I’m best first thing in the a.m., but as the day goes on, I often need to nap as well.”

Schulz isn’t alone. Allergies affect as many as 50 million Americans, and fatigue is a common side effect.

Why Do Allergies Cause Fatigue?

Allergies, especially those caused by pollens, dust, and other airborne substances, can interfere with breathing and prevent a good night’s rest, says Steven Park, MD, an otolaryngologist in New York City and author of the book Sleep, Interrupted.

“When your nose gets stuffy, your tongue starts to fall back, creating a vacuum effect in your throat,” Dr. Park says. “So you keep waking up, because you can’t breathe.”

Allergy patients may also be tired because of their allergy medicine. Some drugs used to control allergies can have drowsiness as a side effect. One example is diphenhydramine, a medication that works by blocking histamines, substances in the body that can cause allergic reactions. “It’s a great antihistamine, but it’s an older one, and it has a sedating effect,” Park says.

Managing Allergies, Allergy Treatment, and Fatigue

If your allergies are making you tired, the first and easiest step is to figure out what’s causing your allergic symptoms, and avoid them. “If you’re allergic to indoor things like dust or mold, you can put a HEPA filter in your bedroom,” Park says. “If you’re allergic to pollen, you might find it helpful to stay indoors and use an air conditioner.”

If it’s your medications that are making you sleepy, asking your doctor about switching to another form of allergy treatment might be helpful. Some of the newer allergy medications are less likely to cause drowsiness, Park says. These include drugs like loratadine (Alavert, Claritin) and fexofenadine (Allegra).

Some patients may also find relief through prescription nasal steroid sprays like mometasone (Nasonex). “These calm down the nasal mucous membrane and prevent the allergic reaction from happening,” Park says. “The downside is you have to use them everyday to get a prophylactic effect.”

Proper timing of medications can also help allergy patients get a more restful night’s sleep. For example, pseudoephedrine (Sudafed and others) — a decongestant commonly taken in conjunction with other allergy medications — can cause sleeplessness, so it should be avoided right before bed. “You have to be careful, because it can stimulate you, and for some people, it can raise blood pressure,” Park says.

Finally, good nighttime habits may help allergy patients improve their sleep quality. Drinking alcoholic beverages right before bed, for example, should be avoided, because alcohol can relax the muscles and cause the tongue to slip backwards and interfere with breathing. Eating late at night is also not advisable, as it can cause stomach acids to reflux into the back of the throat. “Not only does it irritate your throat, it can go into the ears and sinuses and lungs, causing inflammation — and that can keep you from sleeping as well,” Park says.

Return to the Everyday Health Allergy Awareness Month Package.