Ozempic brain fog: is it real?

If you’re taking Ozempic (semaglutide), you’re likely familiar with its most common side effects, such as nausea, diarrhea, and constipation. But if you spend any time on social media, including Reddit or TikTok, you may have heard about “Ozempic brain fog.”

What is Ozempic brain fog, exactly, and is it really caused by Ozempic? Read on as we dive into this potential side effect, and what may be causing it.

The drug’s packaging does not mention brain fog as a side effect of Ozempic. Search for “brain fog” on social media, though, and you’ll encounter several anecdotal reports from people who say they have had similar experiences. People describe Ozempic brain fog as “feeling stoned” or having trouble staying focused, remembering things, or processing information as quickly as they used to. 

For example, in a post titled “Brain fog?” on the r/Ozempic subreddit, user nygenxmom asked:

Is anyone experiencing brain fog while using Ozempic? I feel like my processing time has slowed down along with my digestion. I also find that I have a tough time driving the day after injection.

Is it just me?

A separate post by user dleifrag999 asked a similar question, in the post “Does Brain Fog Ever Go Away?”:

I’m new to Ozempic-on my third week [...]. Is there any hope the brain fog will go away ever?

Right now, it’s tough to say whether Ozempic can cause brain fog. Most of the reports are anecdotal, and there aren’t any published studies showing a causal relationship between Ozempic and brain fog. Still, that doesn’t mean that what some people report isn’t real. 

So while it is possible that Ozempic causes brain fog, it’s also possible that these symptoms could be explained by another side effect, suggests Dr. Rachel Goldman, PhD, FTOS, FASMBS-IH, Licensed Psychologist and Clinical Assistant Professor at NYU Grossman School of Medicine. She doesn’t have any current clients on GLP-1s experiencing Ozempic brain fog, but “there are many things that can cause ‘brain fog’ or mental confusion.” 

“It’s easy to point to a medication and make a generalization about it by saying that X is caused by Y, (similarly to ‘Ozempic face,’ ‘Ozempic personality,’ etc.), but is it really? Further, each individual is different and we need to look at the whole picture, and the whole person, to determine what is really going on. Considering GLP-1s do target the brain though, it is an interesting question if it is the medication that is causing this, but we can’t say with certainty at this time,” says Dr. Goldman.

Ozempic belongs to a category of medications known as GLP-1s. “These medications work by mimicking GLP-1, a naturally occurring hormone, that tells the brain that it is full. It helps control hunger and satiety,” says Dr. Goldman. GLP-1s like Ozempic also influence the brain’s reward center regarding food, which helps reduce cravings and food noise (persistent, intrusive or obsessive thoughts about food). 

Given that GLP-1s work by interacting with the brain, it doesn’t seem completely out of left field that they could have other, brain-related effects besides appetite and satiety. Similar to how Ozempic curbs food cravings, some people report better control over other addictive behaviors like alcohol, drug, and tobacco use, perhaps due to the drug's influence on dopamine signaling. And, studies of social media posts have found a link between GLP-1s and: 

• Depression

• Anxiety

• General mental health

• Suicidal thoughts

• Sleep issues, including insomnia

After they start taking GLP-1s and losing weight, some people report that their depression lifts, while others experience poorer mood and more anxiety. 

GLP-1s may also reduce the risk of dementia in people with type 2 diabetes. And limited research has shown that semaglutide, the active ingredient in Ozempic, may have neuroprotective effects that may prevent or slow the progression of neurodegenerative diseases like Parksinon’s and Alzheimer’s disease.

It’s safe to say there may be ways GLP-1s affect our brain that we simply don’t fully understand yet. 

The science is still out on whether Ozempic causes brain fog. We’ll have to wait for more research, but in the meantime, here are a few other possible causes of brain fog while taking Ozempic. 

Hypoglycemia

Hypoglycemia, or low blood sugar, is more likely when taking Ozempic—especially if you are taking insulin or certain oral diabetes medications that boost insulin secretion. Typically, a healthcare provider will lower your dosage of these medications to prevent hypoglycemia on Ozempic, but it can still occur.

Some of the signs of low blood sugar sound similar to Ozempic brain fog, such as confusion or drowsiness. “Some are referring to ‘Ozempic brain’ as symptoms of hypoglycemia, and when individuals experience that it does impact how their brain functions,” shares Dr. Goldman. Other signs of low blood sugar levels include:

• Dizziness

• Light-headedness

• Sweating

• Headache

• Blurred vision

• Slurred speech

• Shakiness

• Fast heartbeat

• Feeling anxious or irritable

• Hunger

• Weakness

• Feeling jittery  

Not eating or drinking enough

“Maybe the ‘brain fog’ is a result of something else, such as not eating enough or being dehydrated,” says Dr. Goldman. “We know that these medications lead to a decreased appetite, but we also know that decreased food intake, as well as dehydration, can lead to things such as mental confusion, difficulties concentrating, lightheadedness and dizziness, etc. We also know that lack of sleep and even over exercising can lead to one feeling some of those symptoms too.”

Dehydration is a concern with Ozempic, as some of its side effects—notably vomiting and diarrhea—can lead to dehydration if you don’t rehydrate properly. Severe dehydration can increase the risk of kidney issues on Ozempic. To stay hydrated, always have a water bottle on hand. If water’s not super palatable to you, find ways to spruce up your glass by adding some fresh mint or fruit slices. You can also try one of these healthy alternatives.

Your appetite may drop significantly on Ozempic, but if you’re not eating enough nutritious foods, you may not be getting the energetic benefits you need—leading you to feel groggy or low energy. So, try to fill your plate with nutrition-packed, healthy foods first, like proteins, whole grains, fruit, vegetables, beans, legumes, nuts, and seeds.

Depression or fatigue

In Ozempic’s clinical trials, fatigue was reported as a side effect in more than 0.4% of people. It’s possible that what people are describing as brain fog stems from fatigue, which is medically defined as a lack of energy.

And, as we mentioned above, some people may experience depressive symptoms when taking Ozempic. For some, that sense of fatigue or lack of motivation may be a sign of depression, rather than brain fog, says Dr. Goldman. “I think an additional question to ask though is how are we defining ‘brain fog.’ There’s a difference between experiencing depressive symptoms and/or anhedonia [a lack of pleasure or enjoyment from activities you used to find enjoyable] and mental confusion.”

“It’s easy to point our fingers at one thing (these medications) and say that the medication is causing this brain fog, but we really don’t know that without research and the science telling us that,” says Dr. Goldman.

The first step to dealing with Ozempic brain fog is identifying patterns between your symptoms and when they appear, says Dr. Goldman. 

“If someone is experiencing this “brain fog” I would want to first assess what their daily routine looks like,” says Dr. Goldman. “Are they experiencing this before they eat, later in the day after looking at the computer screen all day, when they are outside in the heat, after a night that they had poor sleep etc.?” 

Dr. Goldman says this information is necessary to understand the root cause and possible ways to combat brain fog. 

“For instance, if they are experiencing this after a poor night’s sleep, I would want to focus on improving their sleep. If someone experiences this more prior to eating, I would suggest that they eat a little earlier and not go so long without eating,” she explains. 

If you’re experiencing symptoms that sound like Ozempic brain fog, talk to your healthcare provider. They can help you understand what might be causing it, and offer advice on how to deal with it.

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Current version

July 22, 2024

Written by

Amelia Willson

Fact checked by

Patricia Weiser, PharmD

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About the medical reviewer

Patricia Weiser, PharmD

Patricia Weiser, PharmD, is a licensed pharmacist, health content writer, and medical reviewer with more than a decade of clinical experience in community and hospital pharmacy.