4 Medications That Could Be Making You Drowsy

Can't keep your eyes open during the day? This could be why.

Many of us are more exhausted than ever these days. An Aug. 2021 study found that up to 20 percent of patients who see a primary care provider report fatigue as their chief complaint. Long work hours, too much time spent indoors, excessive screen time, and lack of exercise can all contribute to feeling overly tired. However, the contents of your medicine cabinet could also be the culprit. Medications are prescribed for a reason, but if you're experiencing daytime drowsiness, it's worth talking to your doctor about whether there are alternatives that might work just as well, without the fatigue. Read on for four commonly prescribed medications could be causing your sleepiness.

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Allergy Pills

As the name suggests, antihistamines work to block histamine—a chemical neurotransmitter released by cells in response to allergic reactions, which can cause itching and irritation. These medications are commonly used for seasonal allergies, nasal congestion, hives, and rashes. But they're also good at helping you doze off—so much so that the same active ingredients are often included in sleep aid products and allergy medications. Over-the-counter (OTC) antihistamines include diphenhydramine (Benadryl), which is marketed as an allergy drug, and doxylamine (Unisom), which is a sleep aid. Hydroxyzine (Atarax) is a prescription allergy medication that can also cause drowsiness.

Laura Purdy, MD, MBA, a board-certified family physician in Fort Benning, Georgia, tells Best Life, "[Antihistamines are] related to a part of our brains called the parasympathetic nervous system, and this part of the nervous system has to do with what is the opposite of the fight or flight response. [Therefore], it results in drowsiness, sedation, slowing heart rate, increasing digestion, and other symptoms associated with rest." If you have severe allergies but want to avoid the dozing effect from your antihistamines, consider taking your allergy medication before bed, or ask your doctor about alternative treatments.

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Woman Pinching Her Forehead and Taking Antidepressants
Dragana Gordic/Shutterstock

Antidepressants are among the most widely prescribed medications, and for good reason. Popular antidepressants, such as serotonin reuptake inhibitors (SSRIs), are life-altering drugs that can potentially save people's lives. SSRIs help treat depression and anxiety by regulating serotonin—the "feel-good" brain chemical that plays a critical role in sleep, mood, and emotion. But sluggishness and fatigue are common side effects.

"SSRIs attach to the end of neurons in the brain where serotonin, a signaling molecule in the brain, is allowed to stay between the ends of the nerves at higher concentrations," explains Purdy. "It's common for people to experience tiredness, sedation, or drowsiness when they use these medications." And SSRIs aren't the only type of antidepressant that can cause drowsiness. Trazodone, which belongs to class of antidepressants known as serotonin receptor antagonists and reuptake inhibitors (SARIs), induces sleepiness in 42 percent of consumers, according to the health experts at GoodRX.

Muscle relaxants

Muscle Relaxant for a Sore Back
HENADZI KlLENT/Shutterstock

Anyone who's endured muscle spasms or experienced chronic muscle pain knows that muscle relaxants can be a godsend. But while these medications provide pain relief for those in need, many people dealing with acute neck or back pain are unaware that their muscle relaxants may cause drowsiness and fatigue, according to the American Addiction Centers. Common muscle relaxants include cyclobenzaprine (Flexeril), carisoprodol (Soma), and tizanidine (Zanaflex).

"The exact mechanism of how muscle relaxants cause drowsiness is unknown to a certain extent," Purdy says. "We know that medicines that cause drowsiness do so by working in specific areas of the brain or on certain receptors for hormones or chemicals within the brain that can cause us to be tired. It's believed that muscle relaxants causing sedation are interacting somehow with the serotonin system."

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Beta blockers

Beta Blockers
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Often prescribed to treat high blood pressure and heart-related conditions, beta-blockers are a class of drugs that includes acebutolol, atenolol (Tenormin), bisoprolol (Zebeta), metoprolol (Lopressor, Toprol XL), and others. Because beta-blockers work to lower your heart rate and regulate blood pressure, many users report feeling more exhausted and sleepy than usual. "Beta-blockers are involved in activities such as slowing down the heart rate and lowering blood pressure," says Purdy. "These medications are not sedating, but they can make someone feel tired and fatigued by slowing down the heart rate."

Speak with your healthcare provider if you have concerns about your medications, and ask about ways to reduce sleepy side effects, or whether there's a different medication that might work better for you.

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. When it comes to the medication you're taking or any other health questions you have, always consult your healthcare provider directly.

Adam Meyer
Adam is a health writer, certified holistic nutritionist, and 100% plant-based athlete. Read more
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