Can You Take Lorazepam and Hydroxyzine Together?

Lorazepam and hydroxyzine can be taken together, but doing so increases the risk of heavy sedation, impaired coordination, and slowed breathing because both drugs depress the central nervous system through different pathways. Some clinicians deliberately use the combination in controlled settings like surgical premedication or psychiatric emergencies, but using them together on your own carries real dangers. The interaction is well recognized in pharmacology, and whether the combination makes sense for you depends on the doses involved, your health profile, and whether a prescriber is monitoring you.

Why These Two Drugs Sometimes Show Up Together

Lorazepam is a benzodiazepine, most often prescribed for anxiety, insomnia, and seizures. Hydroxyzine is a first-generation antihistamine with sedating and anti-anxiety properties. Because they calm the nervous system through different mechanisms, there are clinical situations where using both at once is intentional. In one double-blind trial, researchers directly compared intramuscular lorazepam and hydroxyzine as pre-surgery sedatives. Both produced significantly more sedation than placebo within an hour of injection, though lorazepam’s effects lasted longer and more strongly impaired memory of events after the injection.¹ That study used the two drugs as alternatives, but the fact that both were being evaluated for the same purpose shows how closely their sedative effects overlap.

Outside the operating room, hydroxyzine is sometimes prescribed alongside a benzodiazepine to treat anxiety when clinicians want to augment the calming effect without raising the benzodiazepine dose further. A broad review of anxiety pharmacotherapy lists both benzodiazepines and antihistamines like hydroxyzine among the medication classes used to manage generalized anxiety disorder, panic disorder, and social anxiety disorder.² In practice, a provider may use hydroxyzine as a “less addictive” add-on to keep the benzodiazepine dose low, or may prescribe both during a transition period. None of this means the combination is casual or risk-free.

How Each Drug Produces Sedation

The reason combining these two medications is risky starts with how each one slows down the brain. Lorazepam works by binding to a specific receptor complex involved in calming nerve signaling. It enhances the effect of GABA, the brain’s main inhibitory chemical messenger, making neurons fire less readily. Molecular-level research has mapped exactly where lorazepam latches onto subunits of this receptor, and the binding is strong enough to produce not just relaxation but also muscle relaxation, memory loss, and anticonvulsant effects.³

Hydroxyzine takes a completely different route. It blocks histamine receptors in the brain, which is what causes its sedative and anti-itch effects. It also has some anticholinergic activity, meaning it partially blocks the neurotransmitter acetylcholine. The result is drowsiness, reduced anxiety, and dry mouth. In pharmacokinetic studies, hydroxyzine reaches peak blood levels roughly two hours after an oral dose and has a half-life of about seven hours, meaning its sedative effects linger for a good portion of the day.⁴

When you take both, you get GABA enhancement from the lorazepam and histamine blockade from the hydroxyzine hitting the brain simultaneously. Those are two independent braking systems on your central nervous system being activated at once, which is why the sedation can be deeper than either drug produces alone.

The Combined Sedation and Breathing Risk

The most serious concern with the combination is not just that you’ll feel very drowsy. It is that the additive sedation can suppress your drive to breathe. Lorazepam, like all benzodiazepines, is known to reduce the volume of air you move with each breath. Research on patients with chronic lung disease found that benzodiazepines should be used with extra caution because they can compromise respiratory function.⁵ In stable patients with chronic obstructive pulmonary disease, lorazepam reduced the volume of air breathed per minute by about a fifth, driven mainly by shallower breaths and a small rise in carbon dioxide levels in the blood.

Hydroxyzine’s sedation adds to that. While hydroxyzine alone does not carry the same degree of respiratory depression as a benzodiazepine, its sedating effects are genuine. In someone who already has reduced breathing drive from lorazepam, the additional drowsiness and muscle relaxation from hydroxyzine can push things in a dangerous direction. This is especially true at higher doses, in people with sleep apnea or lung disease, and when alcohol is also in the picture.

For most healthy adults taking standard prescribed doses of both medications, life-threatening respiratory depression is unlikely. But the margin of safety shrinks in certain populations, and the combination is not something to experiment with by mixing leftover prescriptions from your medicine cabinet.

Driving and Psychomotor Impairment

Even if breathing is not an issue for you, the practical effects on coordination and reaction time matter in daily life. A review of drug-impaired driving cases submitted to the Washington State Toxicology Laboratory over a six-year period found that lorazepam alone is capable of causing significant driving impairment regardless of the blood concentration detected.⁶ Among the 170 drivers who tested positive for lorazepam, roughly 86 percent also had other drugs in their system, underscoring how commonly lorazepam gets combined with other sedating substances in real-world scenarios.

Adding hydroxyzine to lorazepam compounds that impairment. First-generation antihistamines are well established as causing drowsiness, slower reaction times, and difficulty concentrating. Surgical premedication research confirmed that both drugs individually produce heavy sedation within an hour.¹ If you are taking both, you should assume that driving, operating machinery, and any task demanding sharp reflexes will be compromised for several hours. The lorazepam driving data also showed impairment at a wide range of blood concentrations, meaning you cannot rely on feeling “fine” as a reliable gauge of whether your coordination is actually intact.

A Heart Rhythm Wrinkle Specific to Hydroxyzine

One risk that comes specifically from the hydroxyzine side of this combination is its effect on the heart’s electrical activity. Hydroxyzine has been linked to QT prolongation, a change in the heart’s electrical cycle that can, in rare cases, trigger a dangerous irregular rhythm. A safety evaluation found that among reported cases of QT prolongation and a serious arrhythmia called torsade de pointes associated with hydroxyzine, the most common risk factor, appearing in half of cases, was the combination of an underlying heart condition with other medications that also prolong the QT interval.⁷

Lorazepam itself is not strongly associated with QT prolongation, so the heart rhythm risk here is mostly a hydroxyzine concern. But if you’re taking additional medications that affect cardiac rhythm, or if you have an underlying heart condition, the combination becomes more worrisome. Some European drug agencies have responded to this data by recommending lower maximum daily doses of hydroxyzine and advising against its use in people with known QT prolongation or significant heart disease. This is worth flagging to your prescriber, especially if you are on other medications.

Who Faces the Greatest Risk

Certain groups need to be especially cautious with this combination, and in some cases should avoid it entirely.

Older adults: Both lorazepam and hydroxyzine appear on lists of medications that warrant extra caution in people over 65. Older adults metabolize both drugs more slowly, meaning higher blood levels linger for longer. The sedation, fall risk, confusion, and anticholinergic side effects of hydroxyzine (dry mouth, constipation, urinary retention, blurred vision) are all amplified in aging bodies. Combined, the two drugs substantially raise the likelihood of falls and delirium.
People with lung disease: As noted, benzodiazepines can compromise respiratory function in people with COPD or other chronic lung conditions.⁵ Adding hydroxyzine’s sedation on top increases the risk that breathing slows to a clinically meaningful degree.
People taking other sedating substances: The Washington State driving data showed that 86 percent of lorazepam-positive impaired drivers had additional drugs on board.⁶ If you are already on an opioid painkiller, a muscle relaxant, a sedating antidepressant, or you drink alcohol, adding both lorazepam and hydroxyzine stacks yet another layer of central nervous system depression.
People with heart conditions: The QT prolongation risk from hydroxyzine is amplified when cardiovascular disease is already present or when other QT-prolonging drugs are being used.⁷

Children present a different risk profile. Hydroxyzine’s half-life in pediatric patients has been measured at around seven hours on average, but it increases with age, meaning older children and adolescents may carry higher levels for longer than expected.⁴ Dosing in children requires careful weight-based calculation, and the combination with any benzodiazepine should only happen under close medical supervision.

Using Hydroxyzine to Help Taper Off Lorazepam

Interestingly, one of the most studied clinical uses of these two drugs together is not additive but sequential: using hydroxyzine to help people stop taking lorazepam. Benzodiazepine withdrawal can produce rebound anxiety, insomnia, and in severe cases, seizures. A controlled trial tested six different lorazepam withdrawal methods in patients who had been taking 2 mg of lorazepam daily for at least three months. Patients were randomly assigned to receive either hydroxyzine (at 50 mg or 25 mg) or placebo during the withdrawal period, with either abrupt or gradual tapering. Despite starting with high anxiety scores while still on lorazepam, 75 percent of patients across all groups were completely drug-free after a one-month withdrawal phase followed by two months without any medication, and their anxiety levels had dropped significantly.⁸

The takeaway from this trial was encouraging for people worried about benzodiazepine dependence. Hydroxyzine’s anti-anxiety effect, while milder than lorazepam’s, was enough to smooth the transition for many patients. It also has essentially no addiction potential, unlike benzodiazepines, making it a practical bridge medication. Clinicians sometimes use this strategy when they want to move a patient off a benzodiazepine but need something to manage the anxiety during the transition window. During this tapering period, the patient may technically be taking both drugs at once for a short time, but the goal is to get off the lorazepam entirely.

The Combination in Pediatric Anesthesia Settings

Another context where an antihistamine-benzodiazepine combination shows up is pediatric anesthesia. Young children sometimes experience emergence agitation when waking from certain anesthetics, a distressing period of thrashing, crying, and confusion. A randomized trial in 84 children aged one to seven studied whether adding hydroxyzine to a benzodiazepine premedication reduced this agitation. Children who received the combination had significantly less emergence agitation than those who received the benzodiazepine alone, and the premedication quality was rated higher by the clinical team.⁹

This illustrates an important point: the combination is not categorically dangerous. In a hospital setting with continuous monitoring, the additive sedation is a feature rather than a bug. Anesthesiologists and emergency physicians use it deliberately because they can watch the patient’s breathing, heart rate, and oxygen levels in real time. The danger is mostly in outpatient or unsupervised settings where nobody is watching for signs of excessive sedation or respiratory slowing, and where the doses are chosen by the patient rather than calculated by a clinician.

Practical Guidance if You Are Prescribed Both

If your doctor has prescribed both lorazepam and hydroxyzine, the combination was presumably chosen with awareness of the interaction. Still, a few things are worth keeping in mind. Take the lowest effective dose of each, and do not adjust doses on your own. Avoid alcohol entirely while taking both, since alcohol adds a third layer of central nervous system depression. Do not drive or operate heavy machinery until you know how the combination affects you personally, and be honest with yourself about whether you feel coordinated enough to do so safely.

If you have been prescribed one and are thinking about taking the other from a previous prescription or someone else’s supply, do not do that. The doses used when both drugs are prescribed together are typically lower than when either is prescribed alone, precisely because of the additive effects. Taking a full standalone dose of each is a very different situation than taking the reduced doses a prescriber would choose for the combination.

Tell your prescriber about every other medication you take, including over-the-counter antihistamines, sleep aids, and supplements like melatonin or valerian, which add to sedation. Mention any history of sleep apnea, COPD, or heart rhythm abnormalities. And if you notice extreme drowsiness, shallow breathing, confusion, or a racing or irregular heartbeat after starting the combination, contact your provider or seek emergency care rather than waiting to see if it passes.

When Hydroxyzine Gets Mistaken for a “Safe” Alternative

A common misconception is that because hydroxyzine is “just an antihistamine,” it is inherently safe and can be freely combined with anything. Hydroxyzine does carry a lower risk profile than benzodiazepines in several important ways: it is not addictive, does not cause the same degree of physical dependence, and is not a controlled substance. That is partly why it shows up in anxiety treatment guidelines alongside more potent medications.² But “lower risk” is not “no risk.” Its sedation is real, its anticholinergic effects cause genuine side effects in vulnerable people, and its QT prolongation potential has prompted regulatory action in multiple countries.⁷

People sometimes self-prescribe hydroxyzine for sleep or anxiety because they view it as a gentler option than a benzodiazepine, and they may not think twice about combining it with leftover lorazepam. The interaction between these two drugs is predictable and well characterized, but it is also easy to underestimate if you are thinking of hydroxyzine as just an allergy pill. Treat it as a sedating medication in its own right, and respect the additive effects when anything else that causes drowsiness is in the mix.

1
Anesthesia and Analgesia. A controlled double-blind comparison of intramuscular lorazepam and hydroxyzine as surgical premedicants
2
PubMed Central. Pharmacotherapy of Anxiety Disorders: Current and Emerging Treatment Options
3
Heliyon. Site specific binding pattern of benzodiazepines with GABAA receptor and related impact on their activities in the human body
4
PubMed. Pharmacokinetics and antipruritic effects of hydroxyzine in children with atopic dermatitis
5
PubMed Central. Benzodiazepine use in COPD: empirical evidence from Norway
6
PubMed. Lorazepam and driving impairment
7
PubMed Central. Risk of QT prolongation and torsade de pointes associated with exposure to hydroxyzine: re‐evaluation of an established drug
8
PubMed. Comparison of 6 different methods for lorazepam withdrawal. A controlled study, hydroxyzine versus placebo
9
PubMed Central. A Critical Review of the Psychomotor Agitation Treatment in Youth