Milligram for milligram, Xanax (alprazolam) is roughly twice as strong as lorazepam. A standard equivalence chart from the VA/DoD clinical practice guideline shows that 1 mg of alprazolam produces about the same effect as 2 mg of lorazepam. Both are considered high-potency benzodiazepines, and both work well for anxiety, but they are not interchangeable at the same dose.
How Their Potency Compares
Benzodiazepine potency is measured by comparing each drug to a reference dose of 10 mg of diazepam (Valium). Using that scale, it takes only 1 mg of alprazolam to match 10 mg of diazepam, while it takes 2 mg of lorazepam to reach the same level. Some references, like the widely cited Ashton Manual, place the ratio even higher, listing 0.5 mg of alprazolam as equivalent to 1 mg of lorazepam.
This doesn’t mean Xanax is “better” or more effective. It simply means the active ingredient is more concentrated per milligram. A properly dosed prescription of either drug produces a comparable level of anxiety relief. In a double-blind study of 52 adults with panic disorder, both drugs showed significant and equal anti-panic effectiveness, with participants taking a mean daily dose of about 3 mg of alprazolam versus 7 mg of lorazepam to get there.
Onset, Duration, and How They Feel
Alprazolam tends to kick in a bit faster and wear off sooner. Its calming and sedative effects typically last about eight to twelve hours, which is why it’s often prescribed three times a day. It is classified as a short-acting benzodiazepine, with a half-life ranging from about 6 to 27 hours depending on the person.
Lorazepam is classified as intermediate-acting. It generally lasts a similar window per dose but clears the body at a more moderate pace. In head-to-head memory testing, both drugs caused equally intense sedation and cognitive impairment, but alprazolam produced earlier impairment and earlier recovery, consistent with its faster on/off profile.
How the Body Processes Each Drug
This is where the two medications differ in a clinically meaningful way. Alprazolam is broken down in the liver through a system of enzymes (primarily CYP3A4 and CYP3A5). That means other medications or supplements that use the same enzyme pathway can interfere with how quickly your body clears it, potentially making it stronger or weaker than expected.
Lorazepam takes a simpler route. It’s processed mainly through a different mechanism called glucuronidation, which is less affected by other drugs and less dependent on overall liver function. This makes lorazepam a more predictable choice for people taking multiple medications. For people with significant liver problems, though, neither drug is the top pick. Clinical guidelines for liver disease generally recommend oxazepam or temazepam, which have the simplest metabolic pathways of all.
What Each Drug Is Approved For
Both lorazepam and alprazolam are FDA-approved for treating anxiety. Alprazolam also has a specific approval for panic disorder, which made it the go-to benzodiazepine for panic attacks for years. Lorazepam carries an additional approval for seizures, giving it a role in emergency and hospital settings that alprazolam doesn’t fill.
In practice, doctors prescribe both drugs for overlapping reasons. The panic disorder study mentioned earlier found lorazepam worked just as well as alprazolam for acute panic, suggesting the distinction in FDA labeling reflects the history of which drug was studied for which condition rather than a real gap in effectiveness.
Typical Dosage Ranges
For anxiety, lorazepam is typically started at 2 to 3 mg per day, divided into multiple doses, with a range up to 6 mg daily. Older adults usually start lower, at 1 to 2 mg per day. An extended-release capsule taken once in the morning is also available for people already stabilized on divided doses.
Alprazolam doses are lower in number but not in effect. A typical starting dose for anxiety is 0.25 to 0.5 mg taken three times a day. Because of the 2:1 potency ratio, those smaller numbers deliver a comparable level of relief to the larger lorazepam doses.
Withdrawal and Dependence Risk
All benzodiazepines carry a risk of physical dependence, but shorter-acting drugs tend to produce more intense withdrawal symptoms. Alprazolam has a particularly notable reputation here. According to a VA clinical reference guide, withdrawal symptoms are generally more severe with short half-life benzodiazepines like alprazolam, and withdrawal seizures are more likely with alprazolam than with other drugs in the class. Tapering off alprazolam requires extra caution to avoid reducing the dose too quickly.
Lorazepam, as an intermediate-acting drug, sits in the middle of the withdrawal spectrum. Its symptoms tend to begin within one to seven days after stopping and can last one to two weeks. The experience is still uncomfortable, but the slightly longer duration of action gives the body a bit more of a buffer between doses, producing less of the sharp peaks and valleys that make short-acting benzodiazepine withdrawal especially difficult.
Which One Is “Stronger” in Practice
If you’re comparing pill to pill at the same milligram number, alprazolam is the stronger drug. But strength per milligram isn’t the same as overall effectiveness. When dosed appropriately, both medications produce the same degree of anxiety relief, the same level of sedation, and the same degree of memory impairment. The real differences that matter for most people are practical ones: alprazolam hits faster and fades sooner, lorazepam is processed more simply by the liver, and alprazolam carries a higher risk of difficult withdrawal. Those distinctions, more than raw potency, tend to drive which drug works better for a given person.