If you’ve ever wondered why you feel drained even after a full night’s sleep, your medicine cabinet might hold the answer. Many everyday prescriptions and over-the-counter pills come with a fatigue side effect that can leave you sluggish or foggy during the day. Because these medications are so common, most people never suspect them as the culprit. The result? Persistent tiredness that undermines work, mood, and quality of life. Here are five everyday pills that could be secretly draining your energy—plus what to do about it.
1. Antihistamines
Antihistamines like diphenhydramine (Benadryl) are widely used for allergies and as OTC sleep aids—but they’re notorious for causing drowsiness and fatigue. According to Drugs.com, fatigue is a common side effect, and even “non-drowsy” versions can still leave users feeling sluggish throughout the day . This is because diphenhydramine blocks histamine, a key neurotransmitter that helps us stay alert. Over time, frequent antihistamine use can also increase fall risk and impair memory, especially in older adults . If you’re nodding off mid-afternoon, consider switching to a second-generation antihistamine like loratadine or cetirizine, which are less sedating.
2. Blood Pressure Medications (Beta-Blockers)
Beta-blockers, such as metoprolol, are effective for controlling blood pressure, but many take fatigue as a common side effect. GoodRx notes that users often report feeling unusually tired; this can reflect a slowed heart rate or lowered blood pressure . The Cleveland Clinic also lists fatigue, dizziness, and sleep disturbances as possible effects. The fatigue may result from reduced adrenaline levels and hormonal shifts caused by these medications. Moreover, a review of clinical trials indicates that while fatigue isn’t guaranteed, there’s a small but significant added risk for some patients—especially with older generations of beta-blockers .
3. Antidepressants
Antidepressants—with names like SSRIs, SNRIs, and tricyclics—are lifesavers for many, but they often carry fatigue as a side effect. The Mayo Clinic confirms that fatigue and drowsiness are common, especially in the early stages of treatment. Verywell Mind adds that various types (like SSRIs and SNRIs) can increase sedation by altering neurotransmitters such as serotonin and norepinephrine. Fatigue may also stem from sleeping problems these medications can cause, like insomnia. If your energy plummets after starting an antidepressant, consider adjusting the time you take it or discussing alternatives with your doctor.
4. Pain Relievers and Muscle Relaxants
Prescription pain meds and muscle relaxants might ease aches—but they often slow down the central nervous system, which can leave you feeling groggy. Eureka Health highlights that opioids and certain muscle relaxants can significantly slow your brain or heart activity, resulting in pronounced fatigue . This effect can linger, reducing alertness and daily productivity. Even non-opioid pain relievers can result in mild lethargy when used frequently. Pairing pain management with gentle movement and hydration may help reduce the impact of sedation over time.
5. Sleep Aids (Including OTC Diphenhydramine)
The irony? Sleep aids—especially OTC ones with diphenhydramine—often leave you feeling worse the next day. Time warns of a “hangover” effect, where sleep quality suffers and grogginess persists. Chronic use of such aids may also raise long-term dementia risks, particularly in older adults. Experts now recommend alternatives like cognitive behavioral therapy for insomnia, which won’t threaten your energy levels .
Your Energy Might Be Hiding in Your Medicine Cabinet
Feeling tired constantly isn’t always about poor sleep or stress—sometimes, it’s literally what’s in your pillbox. From allergy meds to antidepressants, common medications can quietly drain your energy. If exhaustion is daily, don’t stop taking your pills abruptly. Talk with your doctor about alternative medications or timing adjustments to help you feel more alert again.
Have you ever suspected a medication was making you tired? Drop a comment below—your insight could help someone finally connect the dots.
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Teri Monroe started her career in communications working for local government and nonprofits. Today, she is a freelance finance and lifestyle writer and small business owner. In her spare time, she loves golfing with her husband, taking her dog Milo on long walks, and playing pickleball with friends.
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