PRN (as-needed) psychiatric medications

Why some medications can be taken as needed and others can't

The question is how fast the drug does its job. A medication that acts quickly on the thing you're feeling can reasonably be taken when that thing shows up. A medication that works by slowly changing brain chemistry over weeks can't.

Take a racing heart before a presentation. Propranolol blunts the body's adrenaline response, so taking it ahead of a known stressful event makes sense. Now take depression. Sertraline doesn't lift mood the afternoon you swallow it. The National Institute of Mental Health notes that antidepressants usually take several weeks of daily use to reach their full effect. Skipping days on and off resets that clock, and it can also cause discontinuation symptoms like dizziness and irritability. The discontinuation syndromes guide explains why.

There's one interesting exception with SSRIs. For premenstrual dysphoric disorder, the FDA label for sertraline includes an option to take it only during the luteal phase, the two weeks or so before a period. That's still a planned schedule set by a prescriber, not "take one when you feel down." For depression, anxiety disorders, and OCD, SSRIs and SNRIs are daily medications.

The medications most often used as needed

Hydroxyzine

Hydroxyzine is an antihistamine that's FDA-approved to relieve anxiety and tension, along with itching and sedation around surgery. Its label says effects usually show up within 15 to 30 minutes, which is what makes it workable as needed. Unlike benzodiazepines, it isn't a controlled substance. Drowsiness is the main tradeoff, and the label cautions against driving or operating dangerous machinery while taking it. It also adds to the sedation of alcohol and other sedating medications, and the label notes a risk of QT prolongation, so tell your prescriber about heart rhythm problems and your other medications. The label also says its effectiveness for anxiety beyond four months hasn't been studied.

Propranolol

Propranolol is a blood pressure medication in the beta-blocker family. It's used off-label for the physical side of anxiety: pounding heart, shaking hands, a trembling voice. NIMH describes beta-blockers as commonly used as needed for predictable performance anxiety, like public speaking.

The evidence has limits worth knowing. A 2024 systematic review and meta-analysis in the Journal of Affective Disorders found no clear benefit of beta-blockers over placebo for social anxiety disorder or panic disorder, though the studies were small. So propranolol can help the shaky-hands problem before a known event, but it isn't a treatment for an anxiety disorder. It isn't safe for everyone either. MedlinePlus lists a slow or irregular heartbeat, heart failure, and asthma or other lung disease among the things to raise before taking it, because a prescriber may decide it isn't right for you.

Benzodiazepines

Lorazepam, alprazolam, and clonazepam are the benzodiazepines most often prescribed as needed, usually for panic attacks or acute, severe anxiety. They work fast and they work well in the moment. That's exactly what makes them tricky.

The real risk with as-needed benzodiazepines

In 2020 the FDA required a boxed warning, its strongest kind, on every benzodiazepine. It spells out the risks of abuse, misuse, addiction, physical dependence, and withdrawal. The FDA noted that physical dependence can develop when benzodiazepines are taken steadily for several days to weeks, even exactly as prescribed, and that stopping suddenly can cause withdrawal reactions, including seizures.

As-needed use doesn't make that risk disappear. It can drift. "Only before flights" becomes "only on bad days," and bad days get more frequent because the medication quietly teaches you that anxiety is something to escape rather than ride out. That's one reason UK guidance from NICE says not to offer a benzodiazepine for generalized anxiety disorder except as a short-term measure during a crisis. Benzodiazepines also combine dangerously with alcohol and opioids, since all of them slow breathing. The benzodiazepine class page and the alcohol and psychiatric medications page cover those risks in more detail.

None of this means a PRN benzodiazepine is always wrong. For some people with occasional, severe panic, a small supply used rarely is reasonable. It works best alongside a treatment that addresses the anxiety itself, like an SSRI or cognitive behavioral therapy, so the as-needed pill stays a backup and not the plan. Shrinkopedia's benzodiazepines overview and its page on panic attacks are good background reading.

How to talk with your prescriber about a PRN plan

A good PRN plan is specific. "Take one if you need it" leaves too much to decide in the moment, when you're least able to decide well. Before you leave the appointment, it helps to know:

What the medication is for, in plain terms. "For a panic attack that hasn't settled after 20 minutes" is clearer than "for anxiety."

The most you should take in a day and in a week, and what to do if you're hitting that limit. Needing it more often is information your prescriber wants, not something to hide.

What not to mix it with, including alcohol, sleep aids, and pain medications.

What the long-term plan is. If you're using an as-needed medication a lot, that's usually a sign the daily treatment needs adjusting.

It also helps to keep a short log: the date, what was going on, and whether it helped. Bring it to your next visit. The PsychiatryRx appointment sheet has space for this.

Don't start, stop, or change a medication, or turn a daily medication into an as-needed one, without talking to your prescriber first.

Common questions

Can I take my antidepressant only on bad days? Usually no. Antidepressants need steady daily dosing to work, and starting and stopping can cause discontinuation symptoms. The planned luteal-phase schedule some prescribers use for PMDD is the main exception, and that's set up by a prescriber.

Is hydroxyzine safer than a benzodiazepine for as-needed anxiety? It isn't a controlled substance and doesn't carry the benzodiazepine boxed warning about addiction and withdrawal, which is why it's often considered first. It can be quite sedating, so it's not ideal before driving or work. Your prescriber can help you weigh it for your situation.

Does propranolol help with anxious thoughts? Not really. It mainly calms the physical signs of adrenaline, like a racing heart and shaking. Research hasn't shown it treats anxiety disorders themselves.

How do I know if I'm relying on a PRN benzodiazepine too much? Signs include taking it more often than you planned, taking it "just in case," running out early, or feeling worse anxiety when a dose wears off. Any of those is worth raising with your prescriber. Don't stop suddenly on your own if you've been taking it regularly, because withdrawal can be dangerous.

Is it okay to drink alcohol if I only take my medication as needed? Alcohol adds to the sedation of hydroxyzine and benzodiazepines, and with benzodiazepines the combination can slow breathing dangerously. Ask your prescriber before combining them.

If you're having thoughts of harming yourself, call or text 988 in the U.S. to reach the Suicide and Crisis Lifeline, or go to the nearest emergency room.

Sources

1. National Institute of Mental Health. Mental health medications.
2. U.S. Food and Drug Administration. FDA requiring Boxed Warning updated to improve safe use of benzodiazepine drug class. 2020.
3. MedlinePlus. Hydroxyzine. and DailyMed. Hydroxyzine hydrochloride tablets prescribing information.
4. MedlinePlus. Propranolol.
5. Archer C, et al. Beta-blockers for the treatment of anxiety disorders: a systematic review and meta-analysis. J Affect Disord. 2025;368:90-99.
6. National Institute for Health and Care Excellence. Generalised anxiety disorder and panic disorder in adults: management (CG113).
7. DailyMed. Zoloft (sertraline) prescribing information.