7 Common Medications That Can Make You Drowsy
Feeling unusually tired after taking a new medication? You’re not imagining things.
Drowsiness is a well-documented side effect of many prescription and over-the-counter (OTC) drugs. While this sedative effect can be helpful in certain situations—like aiding sleep or calming anxiety—it can be a problem when it interferes with work, driving, or daily responsibilities.Here are 7 common medications known to cause drowsiness, why they do it, and what you can do to manage the side effects safely.
1. Antihistamines (First-Generation)
Examples: Diphenhydramine (Benadryl), Chlorpheniramine, Hydroxyzine
First-generation antihistamines are commonly used for allergies, cold symptoms, or sleep. They cross the blood-brain barrier, which leads to a sedating effect on the central nervous system.
Why it causes drowsiness: These medications block histamine in the brain, which regulates wakefulness.
What to do: Use at night if possible, or switch to a second-generation antihistamine like loratadine (Claritin) or cetirizine (Zyrtec), which are less sedating.
2. Benzodiazepines
Examples: Diazepam (Valium), Lorazepam (Ativan), Alprazolam (Xanax)
Prescribed for anxiety, muscle spasms, and insomnia, benzodiazepines are potent sedatives that calm the brain’s activity.
Why it causes drowsiness: They enhance the effect of GABA, a neurotransmitter that promotes sleep and relaxation.
What to do: Avoid operating machinery or driving, especially when starting a new dose. Discuss tapering or alternatives with your doctor if daytime drowsiness is a problem.
3. Sleep Aids and Sedatives
Examples: Zolpidem (Ambien), Eszopiclone (Lunesta), Doxylamine
These medications are intended to induce sleep, so drowsiness is expected. However, lingering grogginess—also called “next-day hangover effect”—is common.
Why it causes drowsiness: These drugs slow brain activity to initiate sleep but may remain in the system longer than expected.
What to do: Use only as prescribed, and make sure you allow a full 7–8 hours for sleep after taking them.
4. Antidepressants
Examples: Trazodone, Mirtazapine, Tricyclics like Amitriptyline
While some antidepressants are activating, others—especially those used off-label for sleep—can cause significant sedation.
Why it causes drowsiness: These medications affect serotonin and norepinephrine pathways and often have antihistamine-like properties.
What to do: Take at bedtime if possible. If drowsiness persists or interferes with daily life, talk to your provider about dosage adjustments or alternative medications.
5. Antipsychotics
Examples: Quetiapine (Seroquel), Olanzapine (Zyprexa), Risperidone (Risperdal)
Used for mood disorders, schizophrenia, and sometimes severe insomnia, many antipsychotics have strong sedative effects.
Why it causes drowsiness: They block dopamine and serotonin receptors and also interact with histamine and acetylcholine receptors—leading to central nervous system depression.
What to do: Timing the dose at night may reduce daytime sedation. Never adjust dosage without medical supervision.
6. Muscle Relaxants
Examples: Cyclobenzaprine (Flexeril), Carisoprodol (Soma), Methocarbamol
Prescribed for back pain, injury recovery, or muscle spasms, these drugs are central nervous system depressants.
Why it causes drowsiness: They decrease the nerve signals in the brain and spinal cord, which leads to overall relaxation and fatigue.
What to do: Avoid alcohol and other sedating drugs when taking muscle relaxants. Use only short-term and avoid driving.
7. Blood Pressure Medications (Certain Types)
Examples: Beta-blockers (Propranolol), Alpha-blockers (Prazosin), Clonidine
Some blood pressure medications can cause fatigue or drowsiness, especially when starting or increasing a dose.
Why it causes drowsiness: These drugs lower heart rate and reduce nerve signals, which can lead to tiredness and low energy levels.
What to do: Talk to your doctor if the fatigue is persistent—other classes of blood pressure meds may have fewer CNS effects.
How to Manage Medication-Induced Drowsiness
- Read labels carefully: Look for warnings like “may cause drowsiness” or “do not operate heavy machinery.”
- Adjust timing: Shifting doses to nighttime may reduce daytime fatigue.
- Avoid alcohol: It can amplify sedative effects dangerously.
- Communicate with your doctor: Don’t stop or change medications without professional guidance.
Final Thoughts
Drowsiness is one of the most common—and sometimes overlooked—side effects of everyday medications. Knowing which drugs are likely to make you sleepy can help you take precautions, plan your day accordingly, and stay safe.
If you’re concerned about how a medication is affecting your energy levels or alertness, talk to your healthcare provider. There may be alternatives or dosage adjustments that preserve your well-being—without leaving you dragging through the day.
Sources
- Mayo Clinic: Medication Side Effects
- FDA Drug Safety Communications
- Cleveland Clinic – Managing Medication Drowsiness
- American Psychiatric Association – Sedating Medications Overview