Temazepam Side Effects: What to Expect and When to Call Your Doctor

If your doctor has prescribed temazepam (brand name Restoril) for a short stretch of sleepless nights, it helps to know what to expect before your first dose. Temazepam side effects are generally predictable — next-day drowsiness, dizziness, and a mild “hangover” feeling are the most common — but the more important story is why this medication is meant to be used for only a week or two at a time, and why older adults in particular need a lower dose and extra caution around falls. Here’s a clear look at what the evidence actually shows.

How Temazepam Works

Temazepam belongs to a class of medications called benzodiazepines. It works by enhancing the effect of GABA, a calming chemical messenger in the brain, which slows down nervous system activity and produces the sedating, muscle-relaxing, anti-anxiety effect that helps you fall asleep. This is the same basic mechanism shared by other benzodiazepines used on this site’s Sleep & Nerve Health topics, including clonazepam. Because temazepam slows down the central nervous system broadly, rather than targeting sleep alone, it can also cause daytime sedation, slowed reflexes, and — especially when combined with other sedating substances — dangerously depressed breathing. This is also why temazepam is approved only as a short-term treatment: the FDA label describes it as indicated for insomnia generally lasting no more than 7 to 10 days, based on clinical trials that ran about two weeks.

Common Side Effects

Based on FDA prescribing information from placebo-controlled clinical trials, here’s how temazepam’s side effect rates actually compared to placebo:

• Drowsiness. Reported in about 9.1% of people taking temazepam, versus 5.6% on placebo — the clearest drug-attributable effect, and the main reason temazepam carries next-day sedation warnings.
• Dizziness. About 4.5% on temazepam versus 3.3% on placebo.
• Lethargy (low energy, sluggishness). About 4.5% versus 3.4% on placebo.
• Fatigue. About 4.8% versus 4.7% on placebo — essentially the same rate, suggesting general tiredness is common among people with insomnia regardless of treatment.
• “Hangover” grogginess. About 2.5% versus 1.1% on placebo — a lingering groggy, foggy feeling the next morning that’s distinct from ordinary daytime sleepiness.
• Nausea. About 3.1%, actually slightly lower than the 3.8% reported on placebo in trials.

Interestingly, a couple of symptoms often assumed to be temazepam side effects — headache and nervousness — were reported at similar or even lower rates on temazepam than on placebo in trials (headache: 8.5% vs 9.1%; nervousness: 4.6% vs 8.2%). That’s a useful reminder that not every symptom people notice while taking a sleep medication is actually caused by the medication; some reflect the underlying insomnia or anxiety itself.

Why Temazepam Is a Short-Term Medication

Unlike daily long-term medications for chronic conditions, temazepam’s FDA approval explicitly covers short-term use — generally 7 to 10 days, and the trials that supported its approval lasted only about two weeks. This isn’t an arbitrary cutoff. The longer a benzodiazepine is used and the higher the dose, the greater the risk of physical dependence, tolerance (needing more to get the same effect), and withdrawal symptoms when stopping. If your insomnia continues beyond the time your doctor originally prescribed, that’s a signal to check in rather than simply continuing to refill the prescription on your own, since your doctor may want to reassess the underlying cause of your sleep trouble or consider a different approach for longer-term management.

What to Expect in the First Few Nights

Temazepam typically starts working within 30 to 60 minutes, which is why it should be taken right before you plan to get into bed, not earlier in the evening while you’re still moving around the house. Most people notice the sedating effect fairly quickly, but how groggy you feel the following morning can vary a fair amount from person to person, depending on your dose, your age, and how your body metabolizes the medication — its half-life ranges from roughly 3.5 to 18 hours, with an average around 8.8 hours, which is part of why some people wake up feeling clear-headed while others feel foggy well into the next morning. It’s worth paying close attention to how you feel the first one or two mornings after starting, before committing to an early alarm, an important meeting, or a long drive. If grogginess is still noticeable by late morning, mention it to your doctor; a lower dose is often enough to resolve it without giving up on the medication altogether.

Dependence, Withdrawal, and the Opioid Warning

Temazepam carries an FDA boxed warning — the agency’s strongest safety warning — covering three related risks. First, combining benzodiazepines like temazepam with opioid pain medications can cause profound sedation, dangerously slowed breathing, coma, or death; this combination should be avoided unless there’s truly no other option, and even then it calls for the lowest effective doses and close monitoring. Second, like other benzodiazepines, temazepam carries a real risk of abuse, misuse, and addiction, particularly when combined with alcohol or other substances. Third, continued use can lead to clinically significant physical dependence, and stopping abruptly or reducing the dose too quickly after regular use can trigger withdrawal reactions that range from rebound insomnia and anxiety to, in more severe cases, seizures. If you’ve been taking temazepam regularly for more than a few weeks, never stop on your own — talk to your doctor about a gradual taper.

Serious Side Effects That Need Prompt Attention

• Doing things while not fully awake. Benzodiazepine sleep aids, including temazepam, have been associated with complex sleep behaviors — sleepwalking, sleep-driving, making phone calls, or eating while not fully conscious, with no memory of it afterward. Tell your doctor right away if this happens, since it typically means the medication should be stopped.
• Severe allergic reaction. Swelling of the face, tongue, or throat, or difficulty breathing, needs emergency care.
• Unusual mood or behavior changes. Worsening depression, confusion, hallucinations, or thoughts of self-harm should be reported to a doctor immediately.
• Signs of withdrawal after stopping or cutting back. Seizures, hallucinations, tremors, or severe anxiety after a dose reduction are a medical concern, not something to manage alone.
• Breathing that becomes slow, shallow, or difficult. Especially in combination with alcohol, opioids, or other sedating medications — this requires emergency attention.

Who Should Use Extra Caution

• Adults 65 and older. The FDA label specifically recommends a lower starting dose of 7.5 mg for people 65 and up, since the risk of oversedation, dizziness, confusion, unsteady movement, and falls increases substantially at higher doses in this age group.
• Anyone also taking opioids, alcohol, or other sedating medications. The combined central-nervous-system-depressing effect can be dangerous, even at usual doses of each individual medication.
• Anyone with a history of substance use, depression, or suicidal thoughts. These warrant a closer conversation with your doctor before starting a benzodiazepine.
• Anyone with sleep apnea or a breathing-related condition. Temazepam’s sedating effect on breathing muscles can worsen these conditions.
• Anyone who is pregnant or planning to become pregnant. Use later in pregnancy has been associated with sedation or withdrawal symptoms in newborns.

Temazepam Compared to Other Sleep Medications

Temazepam is one of several prescription options for sleep covered on this site. Clonazepam is a longer-acting benzodiazepine more often prescribed for anxiety or seizure disorders, but sometimes used off-label for sleep; because it stays in the body longer, it tends to carry more next-day grogginess. Trazodone and mirtazapine are antidepressants frequently prescribed off-label for sleep at lower doses; they aren’t benzodiazepines and don’t carry the same dependence profile, which is part of why many doctors prefer them for longer-term sleep support. For milder or occasional sleep trouble, some people and doctors prefer starting with an over-the-counter approach like a melatonin supplement before moving to a prescription option. The right choice depends on how long the insomnia has lasted, whether anxiety or depression is also part of the picture, and how you tolerate next-day sedation.

Tips for Taking Temazepam Safely

• Take it only on nights you can get a full 7 to 8 hours of sleep. Taking it and then having to wake up early increases the risk of next-day impairment.
• Don’t combine it with alcohol. This significantly raises the risk of dangerous sedation and breathing problems.
• Avoid driving or using machinery until you know how it affects you the next morning. Next-day grogginess can impair reaction time even if you feel awake.
• Use it for the shortest time your doctor recommends. Don’t request refills to extend use beyond the original short-term plan without a conversation.
• If you’re 65 or older, confirm you’re starting at the lower recommended dose. This is a specific, evidence-based safety step, not just a general caution.
• Never stop a long-term benzodiazepine abruptly. Work with your doctor on a gradual taper if you’ve been taking it regularly for more than a few weeks.

When to Call Your Doctor

Contact your doctor if drowsiness or grogginess doesn’t improve, if your insomnia continues past the originally prescribed short-term course, or if you notice yourself needing more of the medication to get the same effect. Seek emergency care immediately for severe breathing difficulty, an allergic reaction, seizures, or any sign of a sleep-related behavior you don’t remember, such as finding evidence you ate, called someone, or drove somewhere overnight.

Frequently Asked Questions

How long can I safely take temazepam?

Temazepam is FDA-approved for short-term insomnia treatment, generally 7 to 10 days. If you need it longer than that, talk to your doctor about reassessing your sleep problem rather than continuing to refill the same short-term prescription indefinitely.

Will I feel groggy the next day?

It’s possible. “Hangover” grogginess and drowsiness are among the most commonly reported effects, so it’s worth seeing how you feel the first time you take it before planning an early wake-up or anything that requires full alertness.

Is it safe to take temazepam with my other sleep or anxiety medication?

Not without checking with your doctor first. Combining temazepam with other sedating medications, opioids, or alcohol can be dangerous, even if each is safe on its own at the prescribed dose.

Can I just stop taking it once I’m sleeping better?

If you’ve only taken it for a few nights, usually yes, but check with your doctor. If you’ve taken it regularly for several weeks or longer, stopping abruptly can cause withdrawal symptoms, so a gradual taper is safer.

Why does my doctor want me on a lower dose than a younger person might take?

If you’re 65 or older, a lower starting dose (7.5 mg) is a specific FDA recommendation, since older adults face a substantially higher risk of oversedation, confusion, and falls at higher doses.

This article is for general educational purposes and isn’t a substitute for personalized medical advice. Never start, stop, or change a prescription medication without talking to your doctor first.

Temazepam can be an effective short-term tool for getting through a rough patch of insomnia, and most of its common side effects — drowsiness, dizziness, mild grogginess — are manageable and expected to ease once treatment ends. The real safety story is respecting the short-term nature of the prescription, being extra cautious about dose if you’re over 65, and never combining it with alcohol, opioids, or other sedating medications without your doctor’s guidance. Used as directed, for the time frame it’s intended for, it remains a reasonably well-understood option for short-term sleep trouble.