Written by Stacia Woodcock, PharmD | Reviewed by Alyssa Billingsley, PharmDUpdated on October 28, 2022
Key takeaways:
- If you’re feeling fatigued, it’s possible your medication is the cause. For example, medications like fluoxetine (Prozac) and propranolol (Inderal) can make you feel tired.
- In some cases, drowsiness will go away over time as your body adjusts to the medication. But in others, this may not be the case.
- If your medication is causing drowsiness, talk to your healthcare provider. They can help decide the best way to manage it.
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When you’re feeling tired, it can be hard to go about your daily activities. This feeling isn’t uncommon. In fact, fatigue is one of the most common complaints people give to their primary healthcare provider. Up to 45% of people experience it, and sometimes it can be hard to pin down the cause.
While certainly not the only answer, medications like fluoxetine (Prozac) and propranolol (Inderal LA) may cause fatigue or drowsiness in some people. And they’re not the only ones. Let’s review some of the common culprits for fatigue.
1. Antihistamines
Antihistamines are medications used for allergies, hives, and itchy rashes. Some are also used to help you sleep.
- Diphenhydramine (Benadryl, ZzzQuil) and doxylamine (Unisom SleepTabs) are both very sedating and are available over the counter (OTC).
- Hydroxyzine (Vistaril) is an antihistamine that requires a prescription and also causes drowsiness.
- OTC medications with “Nighttime” or “PM” in the name, like Tylenol PM, usually contain an antihistamine. It should come as no surprise that they can cause drowsiness, too.
If you’re feeling sleepy from an antihistamine, there may be another option. Several newer antihistamines, like levocetirizine (Xyzal), fexofenadine (Allegra), and loratadine (Claritin) may cause less drowsiness.
2. Muscle relaxants
If you’re taking muscle relaxants, you may not know they can make you feel drowsy. Commonly prescribed muscle relaxants cyclobenzaprine (Flexeril), carisoprodol (Soma), and tizanidine (Zanaflex) can be very sedating.
You should use caution when driving or doing other activities that require you to be alert when taking these medications. It’s also a good idea to avoid alcohol, since it can make your drowsiness worse.
3. Antidepressants
Antidepressant medications are used not only to treat depression and anxiety, but also chronic pain and even insomnia. Several antidepressants may cause fatigue, including:
- Trazodone, an older antidepressant, causes sleepiness in 42% of people taking it. In fact, it’s commonly prescribed off-label for insomnia.
- Serotonin reuptake inhibitors (SSRIs) like escitalopram (Lexapro), paroxetine (Paxil), and fluoxetine (Prozac), taken for depression or anxiety, can make you feel sleepy.
- Serotonin-norepinephrine reuptake inhibitors (SNRIs) are similar medications used to treat depression, anxiety, and sometimes, chronic pain. They include duloxetine (Cymbalta) and venlafaxine (Effexor), and can also cause drowsiness and fatigue.
- Amitriptyline (Elavil) and nortriptyline (Pamelor) are an older type of antidepressant known as tricyclic antidepressants. They’re used to treat depression and anxiety. They’re also used off-label for chronic pain and to prevent migraines. They too can cause drowsiness and fatigue.
Side effects of antidepressants can vary from person to person. It’s possible they can cause drowsiness in some people but be stimulating for others. Keep in mind that many side effects of antidepressants will go away over time. In some cases, you may be able to take your dose in the evening to avoid feeling tired during the day.
But if you’re still feeling drowsy, your healthcare provider may recommend a different medication. One example is bupropion (Wellbutrin). Studies have shown that it’s just as effective as SSRIs for depression. And people taking it may be less likely to experience sleepiness and fatigue. Your healthcare provider can decide if this would be a good option for you.
4. Topiramate
Topiramate (Topamax) causes drowsiness and fatigue in up to 15% of people taking it. Topiramate is commonly used to treat seizures and prevent migraine headaches. It’s also part of the weight loss medication Qsymia (phentermine/topiramate extended release). The medication carries the nickname “Dopamax” because those taking it may feel “dopey.”
Higher doses seem to cause more fatigue than lower doses. If you’re bothered by fatigue, your healthcare provider may have you take topiramate at bedtime. This may help you avoid daytime sleepiness. Or they may change your dose.
5. Beta blockers
Beta blockers can help treat a variety of conditions. They’re commonly prescribed for certain heart conditions, like high blood pressure and irregular heart rate. They can also be used to prevent migraines and control tremors. Some examples of beta blockers are:
- Metoprolol (Toprol XL, Lopressor)
- Carvedilol (Coreg)
- Bisoprolol
- Propranolol
Since beta blockers can lower your heart rate, people who take them may feel more tired than usual. Your healthcare provider may have you start with a low dose and increase it slowly to help lessen fatigue.
6. Opioids
Opioid medications, such as hydrocodone/acetaminophen, oxycodone (Roxicodone), and acetaminophen/codeine, are used for different types of pain. You might take an opioid medication to treat chronic pain, pain after surgery, or pain from cancer.
These medications may cause significant drowsiness. And while they’re often combined with acetaminophen (Tylenol), it’s the opioid that causes drowsiness, not the acetaminophen.
Tramadol is another pain medication that can also cause significant drowsiness. It’s not as strong as other opioids, but it can still have similar side effects when it comes to feeling tired.
Be sure to use caution when driving while taking opioids. If the drowsiness they cause is bothersome, talk to your healthcare provider. They may suggest a different pain medication for you.
7. Benzodiazepines
Benzodiazepines (BZDs) are used to treat anxiety and seizure disorders. They’re also often used for insomnia — so it makes sense that they can make you sleepy.
Some examples include:
- Lorazepam (Ativan)
- Diazepam (Valium)
- Alprazolam (Xanax)
- Clonazepam (Klonopin)
If you take BZDs every day, it’s likely your body will adjust and you won’t feel as sleepy. But if you’re only taking them once in a while, it’s more likely you’ll feel drowsy. Talk to your healthcare provider if you’re feeling too sleepy while taking BZDs. They may change your dose or try a different medication.
What about antibiotics?
If you’re taking an antibiotic, like amoxicillin (Amoxil) or erythromycin (E.E.S., Ery-Tab), you may feel tired. And you’re probably wondering if the antibiotic is making you feel this way. But the truth is, it’s probably the infection itself that’s making you tired. It’s your body’s way of telling you to slow down and rest so it can fight off what’s making you sick.
Some bacteria release toxins as they die, so you may feel more tired once you start antibiotics to treat them. Doxycycline (Doryx) and ciprofloxacin (Cipro) are examples of antibiotics used to treat toxin-releasing bacteria.
Is drug-induced fatigue temporary?
In many cases, drowsiness will decrease or go away over time as your body adjusts to your medication. But that’s not always the case. Some medications may make you sleepy no matter what. Once you stop taking the medication, your energy will usually come back — but you shouldn’t stop your medication on your own.
If you think a medication you’re taking is making you too sleepy, talk to your healthcare provider. They can help make sure there isn’t something else causing your symptoms. They can also make changes to your medication to help reduce it.
The bottom line
If you’re feeling drowsy, your medication may be the cause. Several medications, like diphenhydramine and amitriptyline, may cause drowsiness. Often, this side effect will go away over time as your body adjusts to the medication — but this isn’t always the case. Contact your healthcare provider if you’re feeling too sleepy from your medication. They can help decide on the best course of action.
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