Potty Mouth Mischief: Did Stop-Smoking Chantix Make Mouth Go Rogue?

Americans like to believe that we are fully in charge of our own behavior. We choose what we say, how we drive and whether we pick a fight. So it can be unsettling to imagine that a medicine might alter those choices. Stop-smoking Chantix (varenicline) has helped many people give up cigarettes. But some readers tell us that while taking the drug, they began behaving in ways that seemed completely out of character.

Potty mouth may be the most amusing example. What follows is considerably more serious.

Did Stop-Smoking Chantix Trigger Potty Mouth?

Q. I noticed vile words coming out of my mouth after a week on the stop-smoking drug varenicline (Chantix). I had many “did I really just say that?” moments. I turned into a mean, angry person on this drug.

I decided to go cold turkey instead and went on anti-anxiety meds for three days. That worked for me, and I’ve been totally smoke-free for 18 years now.

A. We have received over a thousand comments about the oral medication varenicline. Some people have been very pleased with their results. For example, Steve said, “Took Chantix; quit smoking. No issues. Wonder drug.”

Others, like you, experienced changes in behavior such as driving recklessly or picking fights. They have reported reactions such as depression, nightmares and suicidal thoughts. We do not know of any way to predict who will benefit and who will react badly. We congratulate you on taking the important step to stop smoking.

That question appeared in our syndicated newspaper column. But it barely scratches the surface of what readers have told us over the years.

Does Stop-Smoking Chantix Really Help People Quit?

A 2023 Cochrane review concluded that varenicline is more effective for smoking cessation than placebo, bupropion (Zyban) or a single type of nicotine replacement such as a patch alone. In the studies Cochrane analyzed, roughly 21 to 25 people out of 100 taking varenicline successfully stopped smoking, compared with about 18 out of 100 taking bupropion or a single form of nicotine replacement.

The authors concluded:

“Varenicline is more effective at helping people to quit smoking than bupropion, or a single form of NRT [nicotine replacement therapy], and may be as or more effective than dual-form NRT.”

That benefit is important. Smoking remains one of the most preventable causes of disease and premature death in the world. But there is a downside to varenicline.

Can Medications Really Change Behavior?

As suggested in our introduction, Americans are great believers in “free will.” We believe passionately that individuals are responsible for their personal actions. When we make the “right” choice, it is because we have thoughtfully decided to act appropriately. And when we make the “wrong” choice, it was because we acted inappropriately and independently of established norms. The idea that a medication could modify our thinking or our behavior is a foreign concept.

Over the last few years we have received hundreds of comments about the stop-smoking drug Chantix. Many people complained about serious side effects including vivid dreams or nightmares, nausea, dizziness, headaches, indigestion, irritability, depression and suicidal thoughts.

Others, however, were pleased that they were able to stop smoking. Some had almost given up on the idea of quitting until varenicline took away their cravings.

The FDA Flip Flops on Stop-Smoking Chantix Warnings

A boxed warning was added to the Chantix prescribing information in 2009. It cautioned in part:

“All patients being treated with CHANTIX should be observed for neuropsychiatric symptoms including changes in behavior, hostility, agitation, depressed mood, and suicide-related events, including ideation, behavior, and attempted suicide.”

There was also this:

“Advise patients and caregivers that the patient should stop taking CHANTIX and contact a healthcare provider immediately if agitation, hostility, depressed mood, or changes in behavior or thinking that are not typical for the patient are observed, or if the patient develops suicidal ideation or suicidal behavior.“

Please note the words:

“Agitation, hostility…or changes in behavior or thinking that are not typical for the patient…”

The FDA modified this warning in 2016 when it removed the black box from the official prescribing information. In other words, the warning was downgraded because the risks were thought to be lower than previously suspected. But they were not removed entirely.

In the “WARNINGS AND PRECAUTIONS” section of the prescribing information you will discover:

“Serious neuropsychiatric adverse events have been reported in patients being treated with CHANTIX. These postmarketing reports have included changes in mood (including depression and mania), psychosis, hallucinations, paranoia, delusions, homicidal ideation, aggression, hostility, agitation, anxiety, and panic, as well as suicidal ideation, suicide attempt, and completed suicide.”

We have always worried that such “warnings and precautions” are mostly ignored by prescribers and by patients. That is why actual stories from visitors to this website can make such cautions far more vivid.

What Some Readers Report about Stop-Smoking Chantix

RA described what happened to a lifelong friend:

“My best friend of 50 years tried everything to quit smoking and tried Chantix. Within 4 weeks his personality completely changed. He became argumentative, sarcastic and difficult to be around.”

His wife noticed it too:

“His wife made a threat to leave him or get off the Chantix, she being a nurse.”

After stopping the medicine, according to RA, his friend’s behavior returned to normal. He unfortunately resumed smoking.

Bonnie had a similar experience:

“I am normally a very happy person and quite easy going.”

Five days after starting Chantix, that changed:

“The least thing made me very angry.”

At the same time, she noticed exactly the effect she had wanted:

“Cigarettes started tasting really nasty so I could understand why it could help a person quit.”

But she stopped taking the medicine because:

“The side effect of anger and hostility made me quit taking it.”

When Success and Side Effects Collide

Another reader identified only as K described this extraordinary tradeoff:

“I love the Chantix as it helped me stop smoking. I found myself angry and lashing out at other[s] over little things, but I thought there has to be some kind of ‘short coming’ to being able to stop smoking and not feel the cravings.”

After stopping the drug, K reported feeling profoundly depressed.

“Confused” wrote after only four days:

“I lost it this morning over an argument that was not a big deal. I’m noticing cravings are going away already. My wife says I need to stop and start something else. I’m confused because it seems to be helping.”

When Behavior Becomes Dangerous

So far, these stories seem somewhat benign. But we have received messages that are really scary.

One man who had smoked or chewed tobacco for 25 years told us that Chantix dramatically reduced his nicotine cravings. Then he began noticing behavior that was completely unlike him:

“Driving extremely fast, drinking too much and not being safe at work.”

He was an electrician, so unsafe behavior on the job was especially alarming. Then one night a stranger made an obscene gesture at him:

“I got into a street fight because a guy flipped me off. I haven’t been in a fight in over 20 years.”

He said the reaction disappeared shortly after he stopped Chantix. Such an account cannot prove that the medicine caused the behavior. Anecdotes are not randomized clinical trials.

But neither should dramatic, unexpected behavioral changes simply be dismissed—especially when the official prescribing information itself continues to warn about aggression, hostility and other unusual behavior.

Alcohol May Complicate the Chantix Story

There is another wrinkle that deserves attention. The current varenicline prescribing information warns that some people have experienced increased intoxicating effects from alcohol while taking the drug.

“Some cases described unusual and sometimes aggressive behavior, and were often accompanied by amnesia for the events.”

Patients are advised to reduce their alcohol consumption until they know how varenicline affects them. That is especially important because several of the frightening stories readers have sent us over the years involved alcohol.

“My husband’s best friend, another soldier, started taking Chantix to quit smoking on Wednesday. Sometime Sunday evening or early Monday morning, he murdered a 17-year-old recruit and shot himself in the head afterwards.
He was the sweetest, kindest, gentlest and most non-aggressive soldier I ever knew. My husband met him in recruiting school, and he was such a smart, talented person.

“We are still struggling with what has happened. But after reading a myriad of stories relating to Chantix, blackouts and violent/suicidal rage, that is the only explanation I have for what happened.

“Our friend had been drinking over the weekend, so I don’t know how much that contributed to his psychosis. Two lives were lost for no reason. We are so frustrated, sad and angry.”

Another reader shared this.

“My husband and I have been married for 36 years. We both started Chantix together. After two weeks I was able to stop smoking. He got down to a couple of smokes a day. That didn’t deter us. We really wanted to quit.

“We went to get our second package of Chantix. The young woman at the pharmacy asked how it was working for us. We both said how happy we were, and that it seemed to be working well. The side effects were seemingly minor.

“On day 35, we got into an argument about something neither of us can now remember. We were drinking alcohol as well. It got BAD! Really Bad! He literally threw me down the hallway, several times. When I tried to get up he either kicked me, or picked me up and threw me again. That was while I was screaming, ‘Please don’t hurt me!’

“My body was covered in bruises. I had a concussion. The bump on my head was as big as my entire hand.

“I would never have thought in a million years that my husband would do that to me. He was arrested and charged with domestic violence. He was also suspended from work.

“My daughter sent me a link to your website and an article about how Chantix triggers violence. I hope my marriage is salvageable. I just don’t know.”

It would be a mistake to assume that Chantix alone caused every such event. Alcohol, nicotine withdrawal, underlying psychiatric conditions and other circumstances can all muddy the picture. But such stories provide texture to the Chantix warning:

“There have been postmarketing reports of patients experiencing increased intoxicating effects of alcohol while taking CHANTIX. Some cases described unusual and sometimes aggressive behavior, and were often accompanied by amnesia for the events.”

The People’s Pharmacy Chantix Survey

Years ago, after receiving hundreds of comments about Chantix, we conducted an informal survey of our readers. We want to emphasize that this was not a scientific study. People who voluntarily respond to an online survey are not necessarily representative of everyone taking the medication.

Nevertheless, the responses demonstrated how different people’s experiences could be.

How helpful was Chantix for quitting smoking?

52.5% found it very helpful
9.5% found it somewhat helpful
19% found it not very helpful
19% said it didn’t work

At the same time:

54.5% said they experienced serious side effects while taking Chantix.

42.9% said they had to stop taking Chantix because of side effects.

And yet:

59.1% said they would recommend Chantix to another smoker, while 40.9% said they would not.

Among the reactions respondents described were trouble sleeping, nausea, vivid or “crazy” dreams, headaches and—in one case—a serious suicide attempt.

Again, those percentages should not be interpreted as the incidence of Chantix side effects in the general population. People who have had an especially good or especially bad experience may be particularly motivated to respond to an online survey.

But the results illustrate something we have heard repeatedly for years: People can have remarkably different experiences with the same medication.

Potty Mouth After Stop-Smoking Chantix Is the Teaser

Someone unexpectedly blurting out obscenities makes an irresistible headline. But potty mouth is not really what this story is about. It is about the unsettling possibility that medicines acting on the brain may sometimes affect much more than the symptom or addiction they were prescribed to treat.

Large controlled trials provide the best evidence we have for determining whether a drug increases a particular risk across thousands of people. But neither should an individual ignore a dramatic behavioral change simply because a large clinical trial found no statistically significant increase in such events overall.

The FDA’s current advice strikes us as sensible: friends and family as well as patients should pay attention to new or unusual changes in mood, thinking or behavior while taking varenicline. And we would add one more suggestion.

Listen when someone who knows you well says, “You’re not acting like yourself.”

Sometimes the person taking a medicine may be the last one to recognize the change.

What About Antidepressants and Violence?

Another class of medications that may affect behavior in some people is antidepressants. Again, healthcare providers and most patients find it hard to believe that a drug designed to alleviate depression could be associated with thoughts of suicide or acts of violence.

Here is an article I wrote over a decade ago:

Antidepressants Linked to Violence: Rape, Robbery and Homicide
A study from Sweden has found an association between antidepressants and convictions for assault, robbery, arson, sexual offense or homicide.

The Swedish study suggested that people between 15 and 24 were more likely to commit violent crimes if they were taking SSRI-type antidepressants. Research since the original 2015 Swedish study has not made the controversy disappear. A 2016 analysis of randomized antidepressant trials found nearly three times the odds of aggressive behavior among children and adolescents taking SSRIs or SNRIs compared with placebo. A much larger Swedish registry study published in 2020 also found a modest increase in violent-crime convictions during periods of SSRI treatment.

Other large observational studies, however, have not found a clear increase, raising the possibility that the underlying psychiatric illness, substance use and other factors account for at least part of the association. The bottom line seems to be that healthcare providers, family and friends must be vigilant for any changes in behavior after someone starts a medication that could impact brain function.

What About You?

Have you ever taken Chantix or generic varenicline to stop smoking?

Did you experience vivid dreams, irritability, anger, depression—or any behavior that seemed unlike you? Or was Chantix the medicine that finally allowed you to quit without difficulty?

What about antidepressant medications? Any changes in thinking or behavior while taking drugs such as duloxetine, fluoxetine, paroxetine, sertraline or venlafaxine?

We are especially interested in hearing from people who had a positive experience, as well as those who encountered problems. Please share your story in the comment section below.

And finally, we would like to learn your perspective about the idea that a medication could modify our thinking or our behavior. Most people find that concept hard to swallow. And yet there are medications that carry warnings about exactly that. The medication pramipexole (Mirapex) is prescribed for restless legs syndrome (RLS) as well as for Parkinson’s disease. Under the category “Impulse Control/Compulsive Behaviors” there is a warning:

“Cases of pathological gambling, hypersexuality, and compulsive eating (including binge eating), and compulsive shopping have been reported in patients treated with dopamine agonist therapy, including pramipexole therapy.”

Do you believe such a thing is possible? Please share your thoughts and experiences in the comment section below.