What Medicines Can Make You Tired?

Medically Reviewed by Carol DerSarkissian, MD on August 07, 2019

You expect to feel tired if you take a sleeping pill, but other kinds of medications can cause fatigue, too. It’s one of the most common side effects of prescription and over-the-counter medicines.

When medicines make you tired, it is often because they affect chemicals in your brain called neurotransmitters. Your nerves use them to carry messages to each other. Some of them control how awake or sleepy you feel.

Medications That Cause Fatigue

Some of the most common drugs that can make you tired are:

Allergy medications (antihistamines), such as diphenhydramine, brompheniramine (Bromfed, Dimetapp), hydroxyzine (Vistaril, Atarax), and meclizine (Antivert). Some of these antihistamines are in sleeping pills, too.

Antidepressants. One type of antidepressant called tricyclics can make you feel tired and sleepy. Some are more likely to do that than others, like amitriptyline (Elavil, Vanatrip), doxepin (Silenor, Sinequan), imipramine (Tofranil, Tofranil PM), and trimipramine (Surmontil).

Anxiety medications. Benzodiazepines like alprazolam (Xanax), clonazepam (Klonopin), diazepam (Valium), and lorazepam (Ativan) can make you feel drowsy or weak for a few hours to several days, depending on which one you take.

Blood pressure medications. Beta-blockers, like atenolol (Tenormin), metoprolol tartrate (Lopressor), metoprolol succinate (Toprol XL), and propranolol hydrochloride (Inderal), to name a few. They work by slowing down your heart, which can make you tired.

Cancer treatment. Different types of cancer treatment can make you very tired by changing protein and hormones levels in your body. As they kill cancer cells, they also damage or destroy some normal cells. Then your body has to spend extra energy to fix or clean up the cells.

Gut medications. Drugs that control nausea, keep you from throwing up, or treat diarrhea can make you sleepy.

Muscle relaxants. Most muscle relaxants don’t work on your muscles directly. Instead, they work on the nerves in your brain and spine to make the muscles relax. Their effects on your nervous system can make you tired. Some common muscle relaxants are carisoprodol (Soma) and cyclobenzaprine (Flexeril).

Opioid pain medications. Opioids act like the chemicals your body makes to control pain, called endorphins. Common ones are morphine, oxymorphone (Opana, Opana ER), oxycodone (OxyContin, OxyIR), fentanyl (Actiq, Duragesic, Fentora), oxycodone and aspirin (Percodan), oxycodone and acetaminophen (Percocet, Roxicet), and hydrocodone and acetaminophen (Lorcet, Lortab, Vicodin).

Seizure or epilepsy medications. Also called anticonvulsants, these medications can work on your brain cells or the chemicals they use to send messages. Some of these drugs are the same ones that treat anxiety, like benzodiazepines. Other common seizure medications are carbamazepine (Tegretol/Tegretol XR/Carbatrol), phenobarbital, phenytoin (Dilantin, Phenytek), topiramate (Topamax), and valproic acid (Depakene, Depakote).

If the kind of medication you take is not listed here, check the label for words like “may cause drowsiness.” That can help you know what to expect while you take it.

What You Can Do

If your medicine makes you feel worn out, don’t stop taking it. You can try other ways to fight the side effect and get an energy boost:

If you’re taking an over-the-counter medication, ask your doctor or pharmacist if there are “non-drowsy” versions of it you can use instead. It’s important to ask to make sure it won’t affect any other medications you’re taking.

Your doctor can help you handle any fatigue you feel from prescription medications. They might:

  • Change your medication
  • Change your dose
  • Tell you to take your medicine at a different time, like in the evening or before bed
  • Prescribe a medication to help you feel alert and awake

Don’t take any medications that are supposed to help you stay awake, unless your doctor says it’s OK.

WebMD Medical Reference



National Sleep Foundation: “Sleepiness, Medication & Drugs: Why Your OTC Medications and Prescription Drugs Might Make You Tired.”

National Institute of Mental Health: “Brain Basics.”

FDA: “Caution: Some Over-the-Counter Medicines May Affect Your Driving.”

National Capital Poison Center: “Antihistamines: Using Them Safely.”

Mayo Clinic: “Tricyclic Antidepressants and Tetracyclic Antidepressants.”

County of San Mateo Health System: “Benzodiazepines.”

American Heart Association: “Types of Blood Pressure Medications.”

American Cancer Society: “What Causes Cancer-related Fatigue?”

Spine-health: “Muscle Relaxants.”

Cedars-Sinai: “Muscle Relaxants for Orthopedic Conditions.” “Narcotic Analgesics (Opioids).”

Epilepsy Foundation: “How Medicines Work.”

Cleveland Clinic: “Epilepsy Medications.”

Kaiser Permanente: “How to Prevent Tiredness or Fatigue Caused by Your Medicines.”

© 2019 WebMD, LLC. All rights reserved.
Click to view privacy policy and trust info