Anxiety medications can cause a wide range of side effects depending on the type of drug, and most people experience at least some during the first few weeks of treatment. The most common issues include nausea, drowsiness, dizziness, weight changes, and sexual dysfunction. Many of these improve as your body adjusts, but some persist and may require switching medications or adjusting your dose.
Several different classes of medication are used to treat anxiety, and each comes with its own side effect profile. Here’s what to expect from the most commonly prescribed types.
SSRIs and SNRIs
SSRIs and SNRIs are the most widely prescribed medications for anxiety disorders. They work by increasing the availability of serotonin (and in the case of SNRIs, norepinephrine) in the brain. Their side effects tend to be most noticeable in the first few weeks, then fade for many people.
Common side effects include nausea, diarrhea, dry mouth, nervousness, shakiness, and changes in appetite that can lead to weight loss or weight gain. A large population-based study published in The BMJ tracked weight changes over time and found that treatment was associated with roughly 2.1 kg of weight gain with one common SSRI and about 4.8 kg with another over two years. So weight changes are real, but they vary significantly depending on the specific drug.
Sexual side effects are among the most persistent and frustrating. About 42% of women taking SSRIs report difficulty reaching orgasm, according to data published in Mayo Clinic Proceedings. Arousal problems affected roughly 82% of patients on one commonly prescribed SSRI, compared to only about 2% of those on a non-serotonin-based antidepressant. These side effects often don’t improve with time the way nausea does, which is why they’re one of the top reasons people stop taking their medication.
Fatigue and drowsiness are also common, especially early in treatment. Nausea typically begins within the first few days and often fades as your body adjusts to the medication, usually within a few weeks.
Benzodiazepines
Benzodiazepines work faster than SSRIs, often within minutes to hours, but they carry more serious risks with regular use. They’re typically prescribed for short-term or as-needed relief of acute anxiety or panic attacks.
Even a single dose can impair memory and attention. With ongoing use, benzodiazepines are associated with falls, fractures, traffic accidents, and delirium, particularly in older adults. Physical dependence can develop relatively quickly, meaning your body adapts to the drug and you experience withdrawal symptoms if you stop abruptly. For these reasons, healthcare providers are generally advised to avoid prescribing them to older adults altogether.
The sedation that makes benzodiazepines effective against anxiety is also their primary side effect. Drowsiness, slowed reaction time, and mental fogginess are essentially built into how the drug works, which makes activities like driving riskier while you’re on them.
Buspirone
Buspirone is an alternative anti-anxiety medication that works differently from both SSRIs and benzodiazepines. It doesn’t cause the sedation or dependence associated with benzodiazepines, and it’s notably less likely to cause the sexual side effects that make SSRIs difficult for many people.
The most common side effects are dizziness, lightheadedness, and drowsiness. Some people also experience nervousness, restlessness, or unusual excitement, which can feel counterproductive when you’re taking it for anxiety. Less common effects include blurred vision, sweating, difficulty concentrating, diarrhea, dry mouth, muscle cramps, ringing in the ears, trouble sleeping, and vivid dreams. Rare but more serious reactions include chest pain, confusion, fast heartbeat, and numbness or tingling in the hands or feet.
Beta-Blockers
Beta-blockers are sometimes prescribed for performance anxiety or specific situational anxiety. They don’t treat the psychological component of anxiety directly but block the physical symptoms, like a racing heart, trembling, and sweating.
Because they slow the heart rate, the main side effects are related to cardiovascular function: fatigue, unusual tiredness, and a slow or irregular heartbeat. Some people notice coldness or tingling in their fingers and toes, especially when exposed to cold temperatures. These drugs can also lower blood pressure, which may cause dizziness when standing up quickly.
The First Few Weeks
If you’re starting an SSRI, SNRI, or buspirone, expect a rough adjustment period. Nausea, sleep disruption, fatigue, and increased anxiety are all common startup effects. For most people, these improve within the first two to four weeks as the body adapts. The therapeutic benefits of SSRIs and SNRIs typically take several weeks to fully kick in, so you may be dealing with side effects before you feel any relief from anxiety. This gap is one of the hardest parts of starting treatment.
Stopping Your Medication
Stopping anxiety medication abruptly can trigger a distinct set of symptoms. With SSRIs and SNRIs, this is called discontinuation syndrome, and it typically begins within two to four days of stopping. Symptoms include flu-like feelings (fatigue, headache, achiness, sweating), nausea, dizziness, burning or shock-like sensations, vivid dreams, and mood changes like irritability and agitation.
Going off antidepressants safely requires a slow, gradual dose reduction. The timeline varies depending on the specific medication and how long you’ve been taking it, so the tapering schedule needs to be individualized. Stopping benzodiazepines can be even more challenging due to physical dependence, and abrupt discontinuation can be medically dangerous.
Serotonin Syndrome
One rare but serious complication to be aware of is serotonin syndrome, which happens when too much serotonin builds up in the body. This most often occurs when two or more medications that affect serotonin levels are taken together. Common combinations that increase risk include taking an SSRI or SNRI alongside migraine medications called triptans, certain painkillers, or even over-the-counter cough medicines containing dextromethorphan. Recreational drugs like MDMA, cocaine, and amphetamines also raise the risk.
Symptoms appear within minutes to hours and include agitation, rapid heartbeat, high blood pressure, fever, heavy sweating, muscle spasms, loss of coordination, and confusion. This is a medical emergency that requires immediate treatment.
Suicidal Thoughts in Young People
All antidepressants carry an FDA boxed warning about an increased risk of suicidal thinking and behavior in children and adolescents. An analysis of 24 clinical trials involving over 4,400 young patients found that the rate of suicidal thoughts or behavior was 4% among those taking antidepressants, compared to 2% on placebo. This risk is highest during the first few months of treatment and during dose changes. It does not mean these medications cause suicide, but young people starting them need close monitoring for worsening mood, agitation, irritability, or unusual behavior changes.