Is There a Drug That Makes You Forget Things?

Several classes of drugs reliably cause memory loss, and they have been used in medicine for decades. Anesthetics like propofol, sedatives like midazolam, and even common substances like alcohol all interfere with the brain’s ability to form or store new memories. What might surprise you is that researchers are also working on drugs that could weaken or erase specific memories after they have already been stored, an area of science that has moved well beyond speculation into clinical trials for conditions like PTSD.

Drugs That Block New Memories From Forming

The most straightforward way a drug can make you forget is by preventing your brain from encoding new experiences in the first place. This is called anterograde amnesia, and it is exactly what anesthesiologists rely on during surgery. Propofol, one of the most widely used anesthetic agents, produces anterograde amnesia in a dose-dependent way, meaning higher doses cause more complete memory gaps.¹ At low, sub-anesthetic doses, propofol does not put you to sleep but still disrupts the hippocampus, the brain region responsible for forming new autobiographical memories. Brain imaging studies show that even mild propofol sedation reduces connectivity between key hippocampal subfields and other brain areas involved in memory.²

Benzodiazepines like midazolam work through a similar principle but via a slightly different pathway. Midazolam is routinely given before procedures precisely because it produces reliable anterograde amnesia: you won’t remember what happens after the injection. Research confirms that higher doses of midazolam increase the likelihood of this memory-blocking effect.³ Both propofol and benzodiazepines act on GABA receptors, which are the brain’s primary braking system. By enhancing GABA activity, these drugs suppress the hippocampal processes that normally cement experiences into lasting memories. Propofol has been shown to interfere with specific hippocampal events called sharp-wave ripples, which are thought to be critical for transferring short-term experiences into long-term storage.⁴

This effect is considered a feature, not a bug, in medical settings. Not remembering a colonoscopy or dental procedure is generally a good thing. But it also means these drugs carry real risks when misused. Some patients under general anesthesia unexpectedly regain awareness during surgery and form traumatic memories of the experience, a phenomenon that highlights just how narrow the window is between amnesia and consciousness.⁵

Anticholinergic Drugs and Memory

A different route to drug-induced forgetting runs through the acetylcholine system. Acetylcholine is a chemical messenger that plays a central role in attention and memory formation. Drugs that block it, collectively called anticholinergics, reliably impair the ability to learn and remember. Scopolamine, originally used for motion sickness, is one of the best-studied examples. In laboratory animals, scopolamine produces dose-dependent drops in memory performance across multiple types of tasks.⁶ In humans, scopolamine disrupts theta oscillations in the hippocampus, a specific brain rhythm that helps coordinate the timing of neural activity during memory formation. The degree to which scopolamine disrupts this timing correlates with the severity of memory impairment in individual people.⁷

What makes this relevant to everyday life is that anticholinergic effects show up in many common medications. Certain antihistamines (like diphenhydramine, the active ingredient in many sleep aids), bladder medications, and older antidepressants all have anticholinergic properties. Most people taking these drugs don’t realize they may be subtly impairing their own memory. This is especially concerning for older adults, who are more vulnerable to these effects because of age-related changes in brain chemistry and drug metabolism.⁸ If you’ve ever felt foggy or forgetful while taking an over-the-counter sleep aid, the anticholinergic mechanism is a likely culprit.

Alcohol, Ketamine, and the Blackout

Alcohol is probably the most commonly experienced amnesia-inducing substance on the planet. Large amounts consumed rapidly can produce either fragmentary blackouts, where you remember some events but not others, or complete “en bloc” blackouts, where entire stretches of time are simply gone. The mechanism is similar to what anesthetics do: alcohol disrupts hippocampal activity, blocking the formation of new autobiographical memories.⁹ The key factor is the speed of drinking. A person who reaches a high blood alcohol level gradually may form hazy memories; the same blood alcohol level reached quickly is far more likely to produce a total blackout.

Ketamine, a dissociative anesthetic now also used to treat depression, impairs episodic memory through a different receptor system. It blocks NMDA receptors, which are essential for a process called long-term potentiation, the strengthening of connections between neurons that underlies learning. Ketamine administration produces episodic memory deficits and disrupts both the frontal and hippocampal brain regions that contribute to encoding and retrieving memories.¹⁰ Other substances used in drug-facilitated crimes, including GHB and various sedative-hypnotics, exploit overlapping receptor systems to produce anterograde amnesia alongside sedation.¹¹

Propranolol and the Idea of Erasing Existing Memories

Blocking new memories from forming is one thing. Weakening or erasing memories that already exist is a much more provocative idea, and it is closer to reality than most people think. The drug that has attracted the most attention in this area is propranolol, a beta-blocker originally designed for heart conditions. Propranolol crosses into the brain and dampens the effects of noradrenaline, a stress hormone that helps make emotional memories vivid and persistent. When propranolol is given shortly before or after someone recalls a distressing memory, it can oppose the emotional enhancement that normally keeps that memory strong.¹²

The theory behind this approach is called reconsolidation. When you actively recall a stored memory, that memory briefly becomes unstable and needs to be “re-saved” through a biological process involving protein synthesis. If you interfere with that re-saving process, the memory can be weakened or altered. In a randomized controlled trial of 60 adults with long-standing PTSD, propranolol given 90 minutes before a brief trauma memory reactivation session once a week for six weeks produced significant reductions in PTSD symptoms compared to placebo. The within-group effect size for propranolol was large.¹³ A subsequent trial using a similar protocol confirmed the treatment’s promise for both PTSD and comorbid depression symptoms.¹⁴

However, propranolol does not literally delete a memory. People still know what happened to them; the treatment appears to strip away the intense emotional charge. Think of it less as erasing a file and more as removing the red exclamation mark that keeps your brain treating the memory as an emergency. And the approach does not always work. Some reviews have noted that propranolol’s impact on patients is inconsistent, and the reconsolidation versus extinction-enhancement debate remains unsettled.¹⁵

Drugs That Help You Unlearn Fear

A related but distinct strategy doesn’t try to weaken the original memory at all. Instead, it tries to strengthen the new memory that forms when you learn that something previously frightening is actually safe, a process called extinction. Exposure therapy already does this: by repeatedly confronting a feared stimulus without anything bad happening, you build a competing memory. The problem is that the old fear memory can resurface, especially under stress. Several drugs have been tested for their ability to make extinction learning stick.

D-cycloserine, which acts on NMDA receptors, and hydrocortisone, a stress hormone, both facilitated fear extinction in people with PTSD symptoms in a randomized controlled study. Participants given either drug before extinction sessions showed reduced fear responses compared to those on placebo.¹⁶ Another promising avenue involves HDAC inhibitors, drugs that influence gene expression by modifying how DNA is packaged. In animal studies, HDAC inhibitors enhanced the consolidation of fear extinction memories.¹⁷ A human trial found that the HDAC inhibitor sodium butyrate moderately improved the long-term retrieval of extinction memories, meaning people were better at remembering that a previously feared stimulus was safe.¹⁸ These drugs don’t make you forget the original event. They help your brain file a stronger update.

Experimental Memory Erasure at the Molecular Level

The most dramatic attempts at memory erasure involve directly tampering with the molecular machinery that holds memories in place. Protein synthesis inhibitors like anisomycin, when injected into the brain shortly after a memory is formed or recalled, can disrupt the process by which that memory is stabilized. In rats, anisomycin injected before or after a stressful experience reduced anxiety and avoidance behaviors a week later.¹⁹ These findings helped build the case that memories depend on new protein production to persist.

But the picture turned out to be messier than expected. When anisomycin was given after animals recalled an already-stored fear memory, the memory appeared to be gone the next day. Yet when researchers waited three weeks, the memory came back, suggesting the drug may have temporarily disrupted the memory’s expression without permanently erasing it.²⁰ This raises a critical question about whether any drug can truly erase a memory or merely suppress its retrieval temporarily.

A similarly tangled story surrounds ZIP (zeta inhibitory peptide), once hailed as a molecular eraser of long-term memory. ZIP was believed to work by blocking PKMζ, an enzyme thought to be essential for maintaining memory at synapses. But mice genetically engineered to lack PKMζ entirely still formed and kept normal memories, yet ZIP still disrupted those memories when injected into the brain. Researchers eventually discovered that ZIP likely acts through its electrical charge rather than through any specific enzyme target, triggering the removal of receptors from the cell surface via a general mechanism.²¹ Other work found that ZIP’s effects on hippocampal activity are comparable to injecting lidocaine, a local anesthetic that simply silences neurons.²² The ZIP saga illustrates how difficult it is to target a specific memory without broadly disrupting brain function.

Electroconvulsive Therapy and Memory

Not every memory-disrupting intervention is a drug, and one of the most potent memory disruptors in clinical use isn’t pharmacological at all. Electroconvulsive therapy (ECT), used primarily for severe depression, has long been known to cause memory side effects. In a carefully controlled study, researchers showed that a single ECT session applied shortly after patients recalled a specific emotional memory selectively disrupted that reactivated memory while leaving non-reactivated memories intact.²³ This was significant because it demonstrated reconsolidation in human episodic memory: the same principle that propranolol exploits, but with a physical rather than chemical intervention. The finding suggested that the window of vulnerability after memory reactivation is not just a laboratory curiosity but a real phenomenon in human clinical settings.

Why Older Adults Are More Vulnerable

Age matters enormously when it comes to drug-induced forgetting. Older adults face a compounding set of risks. The brain’s cholinergic system naturally declines with age, which means drugs with even mild anticholinergic properties can tip the balance toward noticeable memory problems. Changes in how the body absorbs, distributes, and eliminates drugs also mean that the same dose hits harder and lingers longer in an older person. On top of that, older adults tend to take more medications simultaneously, raising the chance of interactions that worsen cognitive effects.⁸

This is not a trivial problem. Some cases of what looks like early dementia in older adults turn out to be medication-induced cognitive impairment. Drugs commonly implicated include certain bladder medications, sleep aids, older-generation antidepressants, and some anti-nausea treatments. If an older family member seems more forgetful than usual, a medication review is a reasonable early step before assuming that cognitive decline is irreversible.

The Ethics of Intentional Forgetting

As the science moves closer to being able to selectively weaken specific memories, the ethical questions become harder to avoid. On the surface, helping someone with severe PTSD feel less tormented by a traumatic memory sounds unambiguously good. But ethicists have raised several concerns that go beyond the obvious safety issues.

One worry is about personal identity. Our memories, including painful ones, shape who we are. Altering them could change a person in ways neither they nor their loved ones fully anticipate. A memory modification that seems targeted could have “insidious effects on the agent’s emotions and personal identity,” particularly because memories are interconnected in ways we don’t fully understand.²⁴ Others have analyzed these concerns through the lens of personal narrative: your life story is not just yours alone but is woven into relationships and communities. Altering a key memory could distort how you relate to the people around you, raising questions about autonomy and relational identity.²⁵

There are also legal implications. If a witness to a crime could have their memory of the event chemically weakened, what does that mean for testimony? If a soldier returning from combat has traumatic memories dampened, does that affect accountability for actions taken during service? These questions have no settled answers, and the science is advancing faster than the regulatory and ethical frameworks needed to govern it.

Your Brain’s Own Forgetting Chemicals

It is worth noting that the brain already manufactures its own memory-modulating substances. Neurosteroids, compounds produced naturally in the brain from cholesterol, act on many of the same receptor systems that amnesia-inducing drugs target. Some neurosteroids enhance GABA receptor activity, others modulate NMDA receptors, and their levels fluctuate with stress, sleep, and hormonal cycles.²⁶ This means your brain is constantly fine-tuning how strongly memories are encoded, consolidated, and retrieved based on its internal chemical state. The drugs that cause amnesia are, in a sense, hijacking systems that already exist to regulate how much you remember and how much you forget. The difference is one of degree and precision. A benzodiazepine floods the system indiscriminately; your brain’s own neurosteroids operate with far more nuance, adjusting memory strength in response to context.

This built-in flexibility is also why sleep deprivation, extreme stress, and hormonal shifts can all impair memory without any drug being involved. The machinery is the same. Drugs just push the dials further than the brain would on its own.