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.