When Allergy or Cold Medicine Makes You Drowsy

Most medications carry the risk of side effects, and one of the more common of these is drowsiness. Those with seasonal allergies, now in full pollinated swing, are especially aware of this.

“Many common over-the-counter and prescription medications can cause drowsiness, including pain relievers, cold and allergy medications, muscle relaxants, sleep aids and some blood pressure medications,” says Dr. Ada Stewart, a family physician in Columbia, South Carolina, and president of the American Academy of Family Physicians. “In addition, some medications used to treat depression and anxiety may cause drowsiness.”

Medications like these work by acting on chemicals in the brain called neurotransmitters. “Our nerves use these neurotransmitters to regulate chemicals like serotonin and histamines, which make us feel different sensations like being sleepy or wide awake,” Stewart explains.

Antihistamines, a central ingredient in most cold and allergy medications, are a primary culprit. And for the more than 50 million people suffering from allergies and hay fever, according to statistics from the U.S. Centers for Disease Control and Prevention, staying alert is a chronic battle.

[Read: Is It COVID-19, Allergies, Flu or a Cold?]

The Role of Histamines

When seasonal and perennial allergens (pollen, dust, pet dander, molds and the like), bacteria, viruses and other unhealthy germs enter the eyes, nose or mouth, the immune system releases histamine, biochemicals that fight these invaders (among other functions), according to the American College of Allergy Asthma and Immunology. In doing so, they dilate blood vessels and cause other responses that lead to allergy and cold symptoms like runny nose, sneezing and itchy eyes, says the American Academy of Family Physicians. Antihistamine medications help control these symptoms by interfering with these unpleasant effects of histamine.

However, histamines are also found in the brain and play a role in wakefulness. So, unfortunately, some antihistamines also disrupt this process. The result: sleepiness.

Older versions of antihistamines that came on the market many years ago (first-generation antihistamines) are most likely to cause drowsiness, says Dr. Christopher Robles, a family medicine and primary care physician with White Plains Hospital Physician Associates in White Plains, New York. The most common one used is Benadryl; other examples are hydroxyzine (Vistaril, Atarax) and chlorpheniramine (Aller-Chlor), he says.

“These drugs make you sleepy because they are able to cross into the brain, where they target the sleep/wake system. However, about 5% of patients will experience the paradoxical reaction of being kept awake by these medications,” Robles says.

[READ: Is It Safe to Take Allergy Medicine While Pregnant?]

How to Combat Drowsiness

Drowsiness is a big inconvenience for people with busy lives. While it’s difficult to avoid drowsiness entirely, there are strategies for keeping that inconvenience to a minimum.

“Whenever possible, such medications should be taken at bedtime,” Stewart says. In addition, “It is best to avoid alcohol and check with your doctor if you have concerns regarding interactions with other medications.”

If you are taking an antihistamine to fight off a cold or a more severe allergy attack, “Be kind to yourself when you are sick,” she says. “Get plenty of rest, eat well and exercise if you are able. If the drowsiness continues or becomes unbearable, talk with your family physician about alternative treatments.”

For example, there’s no way to avoid being drowsy with first-generation antihistamines, Robles says, but more recent versions of antihistamines (second- and third- generation antihistamines) are formulated so they don’t cross the brain barrier as readily, so they don’t cause drowsiness. These include second generation antihistamines like cetirizine (Zyrtec), fexofenadine (Allegra) and loratadine (Claritin). “There are other medications in this class, but they are generally only available by prescription,” he says. Everyone reacts differently to different medications, so ask your doctor about other options and keep trying until you find one that works better for you.

[Read: Sleep Reset: Getting Your Sleep Back to Normal.]

What to Avoid Doing with These Medications

When on these meds, many people experience a “lack of alertness” that can lead to injury to themselves or others. For that reason, both Stewart and Robles say that it’s best not to drive or operate machinery, and to avoid making any big decisions, whenever you are taking a drug that may cause drowsiness.

Also avoid alcohol, which is a sedative and can compound the situation. “And one should not take other sedating medications unless advised to do so by their doctor,” Stewart says.

Always read the label and take medications as prescribed. And discuss use of these medications with your doctor, especially if you are on other medications or have certain medical conditions, Robles adds. “For example, in the elderly and very young children, first-generation antihistamines can cause significant urinary retention,” he says.

“There are many different ways to treat seasonal allergies, which means this is a highly personalized decision for each patient. This is definitely not a one-size-fits-all scenario,” Robles says. “Also, if you know what your specific allergens are, the best thing to do is avoid them if possible.”

Your family pharmacist is also a good source of information if you have questions or concerns regarding how these medications may interact with other meds you are taking. “It’s always better to ask questions than take chances, and we are here to help,” Robles says.

More from U.S. News

8 Surprising Facts About Asthma and Seasonal Allergies

How to Survive Ragweed Allergy Season

9 Most Common Food Allergies

When Allergy or Cold Medicine Makes You Drowsy originally appeared on usnews.com

Update 03/24/22: This story was published at an earlier date and has been updated with new information.

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