Anxiety medications can cause a wide range of side effects, from mild nausea that fades within weeks to sexual problems that persist for months or longer. The specific side effects you experience depend heavily on which type of medication you’re taking. The most commonly prescribed options fall into a few major categories: SSRIs and SNRIs (antidepressants used for anxiety), benzodiazepines, buspirone, and beta-blockers. Each class works differently in the body and comes with its own set of trade-offs.
SSRIs: The Most Common Starting Point
SSRIs are typically the first medication prescribed for anxiety disorders. They work by increasing the amount of serotonin available in your brain. That extra serotonin helps regulate mood over time, but it also affects your gut, sleep cycle, and sexual function, which is where most of the side effects come from.
The most frequent side effects include nausea, diarrhea, headache, dry mouth, sweating, nervousness, trouble sleeping, drowsiness, shakiness, and changes in appetite. Nausea and fatigue tend to hit hardest in the first week or two and often fade as your body adjusts. Sleep problems and dry mouth can also improve, though they sometimes stick around.
Sexual side effects are a different story. Reduced desire, difficulty reaching orgasm, and erectile problems are common, and they don’t always resolve on their own. Research on healthy volunteers found that over 50% developed significant sexual dysfunction while taking SSRIs. In one study, roughly a third of participants still had delayed ejaculation six months after stopping the medication. A larger analysis put the risk of lasting sexual dysfunction after discontinuation at about 0.5%, which is low in percentage terms but affects a meaningful number of people given how widely these drugs are prescribed.
Weight Changes Over Time
Weight gain from anxiety medications tends to be gradual rather than dramatic, but it adds up. A large study tracked several common antidepressants over two years and found measurable differences between them. Sertraline caused barely half a pound of gain at six months but climbed to 3.2 pounds by two years. Escitalopram led to about 1.4 pounds at six months and 3.6 pounds at two years. Paroxetine followed a similar pattern, reaching about 2.9 pounds at the two-year mark. Duloxetine was more modest at 1.7 pounds over two years.
These are averages, so some people gain more and some gain less. Bupropion, which is sometimes prescribed alongside anxiety treatment, was the only antidepressant linked to slight weight loss early on (about a quarter pound at six months), but even that reversed to a 1.2-pound gain by two years.
SNRIs: Similar Profile, With a Twist
SNRIs share most of the same side effects as SSRIs because they also boost serotonin. The key difference is that SNRIs also increase norepinephrine, your body’s “fight or flight” chemical. That additional mechanism can raise blood pressure and cause more pronounced sweating. It can also, somewhat counterintuitively, worsen anxiety symptoms in some people, especially early in treatment. Clinicians tend to be more cautious when prescribing SNRIs for this reason, particularly if your anxiety already runs high.
Benzodiazepines: Fast Relief, Real Risks
Benzodiazepines work quickly, often within 30 minutes, which makes them effective for acute panic and short-term anxiety. But they carry side effects that set them apart from antidepressants, and the risks escalate the longer you take them.
In the short term, expect drowsiness, slowed reaction time, poor coordination, and memory gaps (particularly difficulty forming new memories while the drug is active). These aren’t subtle effects. They can impair driving and make complex tasks genuinely dangerous.
The bigger concern is dependence. Physical dependence can develop after just one month of daily use. Roughly 4 million people in the United States take benzodiazepines daily, and many of them meet clinical criteria for substance dependence. A meta-analysis found that long-term use led to substantial cognitive decline, including problems with memory and processing speed, that did not fully resolve even three months after stopping the medication.
Withdrawal from benzodiazepines can be protracted and uncomfortable, lasting months in some cases. This is why most prescribers limit benzodiazepines to short-term or as-needed use rather than daily long-term therapy.
Buspirone: A Milder Alternative
Buspirone is prescribed specifically for generalized anxiety and works differently from both antidepressants and benzodiazepines. It doesn’t cause dependence and isn’t sedating in the same heavy way, which makes it appealing for people who want to avoid those risks.
Its side effects tend to be milder: dizziness, nausea, headache, fatigue, nervousness, and difficulty sleeping are the most common. Some people also experience lightheadedness, weakness, numbness, or feelings of confusion. These effects are generally manageable and less disruptive than what benzodiazepines or SSRIs produce. The trade-off is that buspirone takes several weeks to reach full effect and doesn’t work for everyone.
The FDA Warning About Suicidal Thoughts
All antidepressants, including SSRIs and SNRIs prescribed for anxiety, carry an FDA black box warning about increased risk of suicidal thinking and behavior in children and adolescents. A combined analysis of short-term trials found that 4% of young people taking antidepressants experienced suicidal thoughts, compared to 2% on placebo. The risk is highest during the first few months of treatment and during dose changes.
This warning applies to people under 25. It doesn’t mean the medications cause suicide attempts in most patients, but it does mean that young people starting these medications need close monitoring, especially in the early weeks. Families and caregivers should watch for unusual agitation, irritability, or sudden mood shifts.
What Happens When You Stop
Stopping anxiety medication, particularly SSRIs and SNRIs, can trigger discontinuation syndrome if you reduce your dose too quickly. This isn’t the same as addiction or relapse. It’s your brain readjusting to lower serotonin levels.
Symptoms typically include flu-like achiness, fatigue, headache, sweating, nausea, dizziness, vivid or disturbing dreams, and mood swings including irritability and rebound anxiety. One of the most distinctive symptoms is a sensation often called “brain zaps,” a brief electrical or shock-like feeling in the head that can be startling but isn’t dangerous. These symptoms usually emerge within days of stopping or sharply reducing the medication and can last from a few days to several weeks.
Tapering slowly, under guidance, significantly reduces the chance and severity of discontinuation symptoms. This is one reason you should never stop anxiety medication abruptly.
When Side Effects Fade and When They Don’t
Many of the most common side effects, particularly nausea, drowsiness, and initial nervousness, improve within the first two to four weeks as your body adjusts. Sleep disruption and appetite changes often stabilize in a similar window. If you can tolerate the first few weeks, there’s a good chance these early effects will settle down.
Side effects that tend to persist include sexual dysfunction, weight gain, and (with benzodiazepines) cognitive dulling. These are the ones most likely to affect your quality of life long-term and are worth discussing with your prescriber early rather than waiting to see if they resolve. Adjusting the dose, switching medications, or changing when you take your pill (morning versus evening) can sometimes make a meaningful difference. Sexual side effects, in particular, are a leading reason people stop their medication, so raising the issue early gives you more options.