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Can Your Medicine Cause Confusion or Memory Loss?

What do you call brain fog--confusion, forgetfulness or memory loss? It can be devastating! Do some drugs increase the risk of dementia?

Have you ever experienced trouble finding the right word? What about forgetting someone’s name you should know? How about having a hard time finding your car at the supermarket or airport? Most of the time health professionals write off such confusion and memory loss as “benign senescent forgetfulness.” Senescent is doctorspeak for aging. Many people assume that aging dulls the brain. There’s a less scientific term for this phenomenon: “senior moment.” It’s another way of saying that older people have momentary lapses in memory or spells of brain fog. But sometimes medication can cause confusion or memory loss. Do doctors warn about meds that mess with your mind?

Speak No Evil About Confusion or Brain Scramble:

The AMA (American Medical Association) offers this opinion about informed consent and medical ethics:

“Informed consent to medical treatment is fundamental in both ethics and law. Patients have the right to receive information and ask questions about recommended treatments so that they can make well-considered decisions about care. Successful communication in the patient-physician relationship fosters trust and supports shared decision making.”

The trouble is that the AMA does not give doctors clear guidance on what informed consent means in practical terms. In particular, there are no rules or regulations about which adverse reactions should be discussed. In one survey, patients wanted to know about the most dangerous and the most common side effects (Drugs & Therapy Perspectives, Feb. 2015).

Doctors who follow the AMA’s ethics guidelines will likely warn patients about really common drug complications. When they prescribe an antibiotic like amoxicillin, they probably mention digestive tract upset. If health professionals write a prescription for the blood pressure pill lisinopril, there is a likelihood they will warn about dizziness or cough. A prescription for the diabetes drug metformin should lead to warnings about diarrhea, indigestion and flatulence.

Patients who are told about side effects such as headache, dizziness, diarrhea, fatigue or rash rarely resist the prescriptions. These seem like relatively minor adverse reactions that can easily be reversed by stopping the medicines.

One complication of drug therapy that is rarely mentioned, however, is forgetfulness. No one wants to experience brain fog or memory problems.

Meds That Trigger Memory Loss or Confusion:

Few people imagine that the medications they are taking could affect their cognitive ability. Health professionals rarely warn patients that a drug for fibromyalgia, overactive bladder, nerve pain or migraines could interfere with thinking or memory.

This is not the kind of side effect that most health professionals want to warn about. Let’s be honest, no one wants to have spells of fuzzy brain or forgetfulness. If a physician or pharmacist cautions a patient that a new medicine might impact cognitive function in a negative way, that person might opt out of the program.

The Confusion Factor Can Be Hard to Diagnose:

It might be hard to distinguish between drug-induced cognitive dysfunction and memory loss that could be attributed to aging. Side effects of medications that mess with the mind may sneak up so gradually that people have a hard time recognizing them.

What Is Brain Fog Anyway?

How would you even know if your medicine is messing with your mind? “Brain fog” is not in the official FDA list of side effects. Nonetheless, most people know what this phrase means. This adverse reaction makes it harder to concentrate or think clearly. Solving problems can become overwhelming.

The FDA refers to cognitive dysfunction with the following language:

difficulty with concentration or attention, confusion, “thinking abnormal,” language problems (including word-finding difficulties), slowed thinking, memory impairment, amnesia, speech disorder, lethargy, disturbance in attention and disorientation.

It is true that any of those problems could be due to benign senescent forgetfulness. Many people, including some younger folks, have difficulty with concentration at some point. A sleepless night, financial difficulties or the loss of a loved one are just a few of the things that can lead to confusion or memory problems. Long COVID can also create confusion or brain fog.

So can a surprisingly large number of drugs. The list of medications that can contribute to brain fog is daunting.

Medicines That Can Cause Confusion:

Anticholinergic Drugs Are Problematic:

Drugs that interfere with the brain chemical acetylcholine are especially worrisome. Doctors have known for more than 100 years that such “anticholinergic” medications can lead to memory problems. That’s because doctors used to employ such medications to obliterate the memory of painful events.

At the turn of the 20th century, German obstetricians used a powerful anticholinergic drug called scopolamine together with morphine during labor and delivery. This drug combination created something they referred to as Dammerschlaf. That’s loosely translated as “twilight sleep.”

The new mothers did not remember the pain of childbirth. The doctors of the day called this state “clouded consciousness with complete forgetfulness.”

At that time, doctors assumed that the effect wore off quickly and there was no reason to worry about other anticholinergic medications. Now, however, research indicates that regular exposure to such drugs may interfere with cognitive ability later in life. You can read about the evolution of Dammerschlaf and the red flag of anticholinergic drugs at this link. We fear that most physicians are still not aware of the many meds that can cause anticholinergic confusion.

A Modern Tale of Scopolamine Delirium:

We recently received this message from a concerned wife:

Q. I read recently in your column about an amnesia reaction to scopolamine. I would like to share my husband’s scopolamine story.

When he has had surgery in the past, the doctors have applied a scopolamine patch before the operation to prevent nausea and vomiting due to anesthesia and surgery. He’s never had a problem previously, but the patch was not removed following his most recent surgery.

A day later, he became agitated and confused and had to be readmitted to the hospital. He completely lost touch with reality.

Ultimately, an astute pharmacist diagnosed a scopolamine overdose. After two days of terror for me, they removed the patch, and his personality was restored.

Our hospital had never experienced this type of reaction. Thanks to a very attentive pharmacist and a cooperative hospitalist, our anesthesiologists are now advised of the possibility of scopolamine overdose if the patch is not removed before discharge.

A. Scopolamine (Transderm Scop) is a powerful anticholinergic drug. That means it dries up mucus secretions and helps prevent nausea and vomiting. Doctors often prescribe it prior to surgery or to control motion sickness. The official prescribing information states:

“Remove the transdermal system 24 hours following surgery.”

Side effects may include agitation, confusion, blurred vision, dry mouth and memory problems. Some people can experience delusions, paranoia and hallucinations. Thank goodness for the alert pharmacist who recognized symptoms of scopolamine overdose.

The Anticholinergic “Load”

A review of the medical literature concluded that anticholinergic drugs could increase the risk for dementia (Neuroscience and Biobehavioral Reviews, Aug. 2021). In particular, the authors identify drugs to treat overactive bladder, Parkinson’s disease and depression as contributing to the risk.

People who take several different drugs with anticholinergic side effects may be especially vulnerable. That’s because the combined “burden” or “load” of reduced acetylcholine activity can hinder brain function (Clinical Drug Investigation, April, 2021).

Scores of drugs have anticholinergic activity. To find a comprehensive list of such medications, you may wish to click on this link. We suspect you and your doctor will be surprised to see how extensive this list is.

You may also want to take a few minutes to listen to our interview with Dr. Shelly Gray. She and her colleagues studied the cumulative effect of anticholinergic drugs on development of dementia. Here is a link to that free podcast.

Antiepileptic Drugs (AEDs) Can Cause:

“cognitive-related dysfunction: confusion, psychomotor slowing, difficulty with concentration/attention, difficulty with memory, speech or language problems, particularly word-finding difficulties.”

The FDA requires another serious warning with AEDs:

“The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed.”

Of course people with epilepsy cannot stop taking their medicine. They can ask the neurologist for an AED that is less likely to cause cognitive difficulties.

You Could Be Taking an AED and Not Know It:

Before you say you don’t have epilepsy and assume that you are not taking such medicines, be aware that health care providers often prescribe them to treat pain. People with migraines frequently take topiramate (Topamax) to prevent their headaches. Some doctors use it off label to treat bipolar disorder, post-traumatic stress disorder (PTSD) and obsessive compulsive disorder (OCD).

Gabapentin (Neurontin) and pregabalin (Lyrica) are also prescribed for nerve pain (neuropathy or neuralgia). In addition, Lyrica is a mainstay in the treatment of fibromyalgia. At last count, more than 10 million people take one or the other of these drugs.

Fuzzy Brain with Pregabalin (Lyrica) and Gabapentin:

These drugs can cause confusion and “thinking abnormal.” The FDA describes it this way:

“Thinking abnormal primarily consists of events related to difficulty with concentration/attention but also includes events related to cognition and language problems and slowed thinking.”

Sounds a lot like brain fog to us. One reader wrote to tell us about his experience:

“I was placed on Lyrica way back in 2010 for persistent foot and ankle pain following surgery. When I was diagnosed with reflex sympathetic dystrophy four years later, the doctors upped the Lyrica and then added other meds of a similar variety such as Topamax. I went so far into a ‘Lyrica fog’ that I can barely remember anything from those years. Suffice it to say that my profession was ruined.

“I still have significant memory issues even though my new doctor weaned me off Topamax and Lyrica in 2016. I felt like I had a helmet on my head the entire time I used that drug. Once it was gone, so was that feeling.”

Another reader, Brenda in Houston, offered this reaction to gabapentin:

“I can say that gabapentin gave me extreme brain fog and confusion. As a result, I couldn’t cook because I would wander off with food cooking and burn the pan so badly I would have to rush it outside until the smoke cleared. Really, I began to fear I would burn my house down!”

Lucy was caught between a rock and a hard place. She has terrible nerve pain. Gabapentin or pregabalin were the only treatments her doctor had to offer:

“I am no longer the vibrant, independent, smart, confident person I used to be. Gabapentin has caused confusion, foggy thoughts, dizziness, depression, lethargy, slurred words and difficulty concentrating.”

Other Rx Meds & Brain Fog or Memory Loss:

There are so many medications that can cause confusion or memory loss that it would be hard to list them all. A systematic review in the journal Drugs & Aging (Aug. 2012)  describes medications that affect the GABA neurotransmitter system. They are called GABA agonists, gabapentinoids or GABAergics. You can learn much more about them at this link.

New Concerns About Gabapentin and Pregabalin (Lyrica) for Nerve Pain

Benzos and the Brain:

GABAergic drugs also include benzodiazepines or benzos for short. Here is a list:


  • Alprazolam
  • Clonazapam
  • Diazepam
  • Flurazepam
  • Lorazepam
  • Midazolam
  • Oxazepam
  • Temazepam
  • Triazolam

Benzos may have a negative impact on cognitive function  (Journal of Affective Disorders, Oct. 1, 2022). These are also referred to as anti-anxiety medications.

The authors of the 2012 article in Drugs & Aging note that for short-acting and intermediate-acting benzos there was evidence of decrements in cognitive function tests.

“Consistent findings predominantly affecting memory storage, but also impacting attention, reaction time and specific psychomotor functions, characterized single- and repeated-dose studies, without development of complete tolerance over 3 weeks administration.”

Sleeping pills may also contribute to forgetfulness in some people. Benzos have often been prescribed for insomnia, but they are associated with cognitive impairment in middle-aged and older people (Frontiers in Human Neuroscience, Dec. 9, 2021).

Non-Benzo GABAergic Z-type Sleeping Pills

  • Zolpidem
  • Zopiclone
  • Zaleplon

There are inconsistent results regarding the Z-drugs.

One review published in the Journal of Medical Toxicology (June, 2013) concluded:

“Z-drugs, in particular zopiclone, appear to have similar adverse effects to their predecessors, the benzodiazepines. The residual effects on human performance and driving impairment of Z-drugs are derived from their GABA-ergic action and pharmacokinetic profiles. Z-drugs, especially zolpidem, are associated with complex behaviors, hallucinations, and memory impairment. The increased risk of falls and motor vehicle collisions is notably significant for elderly insomniacs on Z-drugs. The risk–benefit analysis of Z-drugs for the management of insomnia in the elderly may not favor treatment.”

Other drugs that may trigger confusion, brain fog and memory loss include older-generation antidepressants called tricyclics. They include medications like amitriptyline and imipramine. Such drugs are sometimes prescribed off label for insomnia.

Anticholinergic medicines prescribed for overactive bladder and incontinence may also impact the brain. Such drugs include fesoterodine, oxybutynin and tolterodine. Older people are especially vulnerable to anticholinergic side effects.

Here is a story from Carol about her mother’s experience:

“My mother was deteriorating before our eyes. I was disappointed in the care she was getting at home and asked her to visit and see my physician for a consultation.

“My doctor took her off tolterodine and Norvasc immediately. He also changed another medication she was taking for cholesterol control. He substituted a natural supplement.

“Her blood pressure stayed in an acceptable range with some moderation in her diet. She added half an hour of walking each day. Her brain fog (mimicking dementia) lifted almost immediately. Her cholesterol also went to an acceptable level, and all the terrible drug side effects were gone. She is absolutely fine today.”

Over-the-Counter Antihistamines & Sleeping Pills:

Even over-the-counter drugs can impact the brain. Diphenhydramine (DPH) is the “PM” in many nighttime pain relievers. It is the antihistamine in the allergy drug Benadryl.

A reader shared this experience:

“I’d fallen and was in discomfort from the bruises, so I took Aleve PM for five straight nights. Talk about brain fog! I couldn’t remember people’s names at work or finish Sudoku puzzles (usually my favorite). I had lots of other brain glitches but didn’t know why. After reading about Aleve PM, I didn’t take it last night and I’m 100 percent better today.”

Diphenhydramine is considered an anticholinergic medicine. It to0 affects the brain chemical acetylcholine. Many people are susceptible to confusion, memory problems and other difficulties when they take such medications.

Sometimes older adults are diagnosed with dementia although the problem is caused by one or more anticholinergic medicines they are taking. When the drugs can be discontinued, the brain fog often goes away. Of course NO ONE should EVER stop any medication without carefully consulting the prescribing physician. Some medications can cause very serious withdrawal symptoms if stopped suddenly! That is especially true of short-acting benzodiazepines.

To find a free list of anticholinergic medicines, search www.PeoplesPharmacy.com for “list of anticholinergic drugs.” Here are some links:

Anticholinergic Drugs | Dry Mouth and Alzheimer Disease?

Where Can I Find A List of Anticholinergic Drugs?

Share your own story about brain fog, confusion or memory loss in the comment section below.

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Joe & Terry

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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  • Tannenbaum, C., et al, “A Systematic Review of Amnestic and Non-Amnestic Mild Cognitive Impairment Induced by Anticholinergic, Antihistamine, GABAergic and Opioid Drugs,” Drugs & Aging, Aug. 2012, DOI https://doi.org/10.1007/BF03262280
  • Gunja, N., “In the Zzz Zone: The Effects of Z-Drugs on Human Performance and Driving,” Journal of Medical Toxicology, June, 2013), doi: 10.1007/s13181-013-0294-y
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