Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 11/13/2020
Selective serotonin reuptake inhibitors, or SSRIs, are a class of antidepressants. They’re widely prescribed to treat a diverse range of mood disorders, including depression and certain forms of anxiety.
SSRIs are the most common type of antidepressant. They work by increasing the levels of the neurotransmitter serotonin in your brain -- a neurotransmitter that’s closely linked to depression and other mood disorders.
Although SSRIs are generally safe and effective, they can cause side effects. Some side effects of SSRIs are mild and temporary, while others can be severe, long-lasting and frustrating to deal with.
Below, we’ve listed the side effects you may experience while using an SSRI. We’ve also talked about what you can do if you experience side effects from an SSRI, from switching medications to making certain changes to the way you use your medication.
SSRIs are a class of modern antidepressants. They were first introduced in the late 1980s and eventually grew to replace older antidepressants, such as tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs).
To a large extent, SSRIs became the first choice medication for treating depression as they’re less likely to cause interactions, dangerous reactions and side effects than older medications used to treat depression.
SSRIs work by increasing the amount of serotonin in your brain.
Although they’re best known as treatments for depression, some SSRIs are also prescribed to treat anxiety disorders, such as generalized anxiety disorder (GAD).
Common SSRIs include Fluoxetine (sold as Prozac®), Sertraline (Zoloft®), Paroxetine (Paxil®), Escitalopram (Lexapro®) and Citalopram (Celexa®).
While SSRIs are generally less likely to cause side effects than older antidepressants, they can still cause certain side effects for users.
Like with many other medications, the side effects from SSRIs occur during the first few weeks of treatment.
Over time, many people who experience side effects notice that they gradually go away as their body becomes accustomed to the medication.
However, some people who use SSRIs experience persistent side effects that don’t disappear over time. Although it’s uncommon, some SSRIs may also cause serious side effects that are harmful to your health.
Research shows that SSRI side effects are often dose dependent, with higher doses of SSRIs more likely to cause certain side effects.
Below, we’ve listed the most common side effects associated with SSRIs.
We’ve also provided information on how frequently each side effect occurs, as well as the steps you can take if you experience each side effect after starting treatment with an SSRI.
Nausea is one of the most common side effects of almost all SSRIs. For example, clinical trials of fluoxetine (Prozac) found that 22 percent of people who used fluoxetine in a trial experienced some degree of nausea.
Likewise, clinical trials of escitalopram (Lexapro), sertraline (Zoloft) and other SSRIs also found that nausea was one of the most common side effects experienced during treatment.
Although percentages can vary from one SSRI to another, about a quarter of all people who use SSRIs experience nausea.
If you’re prescribed an SSRI and experience nausea, there are several things that you can do to potentially make it less severe:
Take your SSRI with food, unless your healthcare provider has recommended that you take it without food. If possible, try to eat smaller meals on a more frequent schedule to prevent nausea.
Use an antacid, such as bismuth subsalicylate (sold as a generic or as Pepto-Bismol®), when you experience nausea symptoms.
Keep yourself hydrated by drinking plenty of water. Although recommendations can vary depending on your size and activity level, drinking eight glasses of eight ounces of water each is a good daily target for most people.
Give it time. Nausea often occurs during the first few weeks of treatment with an SSRI. If you’ve just started using antidepressants, it may disappear as your body becomes used to the effects of the medication.
If you experience persistent or severe nausea from an SSRI, it’s best to talk to your healthcare provider. They may recommend adjusting your dosage or switching to a medication that’s less likely to make you feel nauseous.
Insomnia is a common side effect of many antidepressants, including SSRIs. For example, data for fluoxetine (Prozac) shows that almost 20 percent of people experienced insomnia in clinical trials. Many other SSRIs have similar reported rates of insomnia.
If you’ve recently started using an SSRI to treat depression or anxiety, you may find it difficult to fall asleep after you go to bed at night. You may also find yourself waking up occasionally during the night and struggling to stay asleep without interruptions.
These effects on your ability to fall asleep at night may affect your energy levels during the day, causing you to feel tired and drowsy. To deal with insomnia from an SSRI, you can do several things:
Avoid drinking coffee or any other beverages that contain caffeine, especially late in the day. Caffeine can have an elimination half-life of five hours in healthy adults and may be up to 10 hours in other individuals, meaning an afternoon coffee could make it significantly harder for you to fall asleep.
Try to exercise every day. While there’s no need to complete an intense workout every day, doing 30 minutes of aerobic exercise (for example, a short walk, jog or bike ride in your local park) may be enough to have a positive effect on your ability to sleep.
Take other steps to get better sleep. Simple things like sleeping at the same time every night, meditating and turning off electronic devices late at night can all help you to sleep better.
Like other SSRI side effects, insomnia may disappear over time. However, if it doesn’t, it’s best to talk to your healthcare provider.
Depending on the severity of your depression, anxiety or other mood disorder and your level of difficulty sleeping, they may recommend adjusting your dosage.
In some cases, they may also suggest using a different medication to help you fall asleep more easily.
Many people experience somnolence, or drowsiness, after starting treatment with an SSRI. These side effects are common with many different antidepressants and often develop during the first few weeks of treatment.
Some people may also find that they need to sleep for longer than the normal amount of time while using SSRIs.
Research indicates that some SSRIs may affect your sleep architecture, causing different brain activity during nighttime sleep than you may normally experience.
If you feel drowsy, fatigued or generally tired during the daytime while using an SSRI, you can try the following things:
Stay active. Just like with insomnia, staying active can help you to stay alert and full of energy during the daytime. Research shows that regular, low-intensity exercise reduces fatigue in people who otherwise don’t exercise.
Take a nap during the day. Napping has numerous benefits, with research suggesting that taking a 10 to 20 minute “power nap” during the day may help to provide recovery benefits without causing you to feel groggy afterwards.
If you feel tired during the day, consider taking your SSRI before bed. This may help to reduce any drowsiness you experience during the day. As always, make sure to talk to your healthcare provider before making any changes to your use of your medication.
As with many other SSRI side effects, drowsiness is most common during the first few weeks of treatment.
If you experience persistent drowsiness that doesn’t seem to improve, it’s best to talk to your healthcare provider about adjusting your dosage.
Sexual side effects are a common, frustrating issue for many people who use antidepressants, including SSRIs.
In fact, SSRIs (as well as similar medications called serotonin-norepinephrine reuptake inhibitors, or SNRIs) are particularly associated with sexual side effects.
Research shows that some level of sexual dysfunction may occur in 40 to 65 percent of people who use SSRIs.
Other studies have found even higher incidence rates of sexual side effects in people who use SSRIs -- in one study, as high as 73 percent of all patients.
Put simply, sexual side effects are very common with SSRIs, although they’re not always severe or problematic.
In men, potential sexual side effects caused by SSRIs can include a weaker sex drive, difficulty becoming sexually aroused, erectile dysfunction and delayed orgasm.
Some people may even find it impossible to orgasm during sex while they’re being treated with an SSRI.
These side effects can vary significantly in severity from one person to another. They may occur more often in older people who use SSRIs than in younger people.
If you experience sexual side effects after starting treatment with an SSRI, the following things may help:
Switch to a different medication. Some non-SSRI antidepressants, such as bupropion (sold as Wellbutrin®), have a significantly reduced risk of causing sexual side effects than SSRIs. These medications are also effective at treating depression for many people. In some cases, your healthcare provider may recommend using bupropion at the same time as your SSRI -- a common approach for dealing with sexual side effects.
Have sex at certain times of day. If you notice sexual side effects at one time of day, but not at others, you may be able to schedule your sexual activity around your medication’s side effects.
Try other techniques. Other ways to improve your sexual performance while using SSRIs may include changing the time at which you use your antidepressants or going on a drug “vacation,” in which you briefly stop using your medication. If this is something you are interested in doing, please make sure to discuss with your healthcare provider before stopping your medication.
Like with other SSRI side effects, it’s best to talk to your healthcare provider if you don’t notice any improvement in sexual side effects over time.
They may suggest reducing your dosage or changing to a medication with a lower risk of causing sexual side effects.
Antidepressants can affect the salivary glands, causing you to develop a dry mouth. Although dry mouth is less common with SSRIs than with older antidepressants, research indicates that SSRIs can still cause a significant reduction in your body’s production of saliva.
Because saliva is important for more than just lubricating your mouth, people who experience this side effect may also develop dry lips, a sore throat, an altered sense of taste and difficulty maintaining fresh breath. You may also find it difficult to chew or swallow food.
Like with other common SSRI side effects, there are numerous steps that you can take to deal with dry mouth. Try the following techniques:
Chew sugar-free gum. Research shows that chewing sugar-free gum helps to increase saliva flow, lubricating your mouth and making chewing and swallowing food easier. If you’re prone to dry mouth, try keeping a pack of chewing gum nearby if needed.
Try not to eat salty or spicy foods. These can irritate your mouth and make the effects of dry mouth more noticeable. If you do eat something salty or spicy, drink plenty of water to wash any remaining salt out of your mouth.
Avoid cigarettes and other tobacco products. Tobacco can dry out your mouth, making this side effect worse. Some antidepressants, such as bupropion, may make it easier to quit smoking, making this a great time to look into your options for quitting.
Avoid caffeine. Caffeine may be great for an energy boost, but it can dry out your mouth and make lack of saliva worse. Likewise, alcohol is a common irritant that can worsen the symptoms of dry mouth.
Sip on water throughout the day. Try keeping a water bottle within reach during the day to help when your mouth becomes overly dry. If water is too bland, try a sugar-free drink or suck on ice chips to keep your mouth hydrated.
If you don’t experience any improvement over time, talk to your healthcare provider. They may recommend adjusting the dosage of your SSRI or switching to a different category of medications.
Alternatively, they may prescribe a medication such as pilocarpine (Salagen®) or cevimeline (Evoxac®) to treat this side effect.
These medications help to stimulate saliva production to keep your mouth lubricated and make talking, chewing and swallowing easier.
Antidepressants are commonly associated with weight gain. While SSRIs generally don’t have as much of an effect on body composition as older antidepressants, research shows that most SSRIs are linked to some degree of weight gain over the long term.
For example, a study that compared antidepressants found that the SSRIs fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil) and citalopram (Celexa) were associated with an increase in weight and body mass index (BMI) amongst users.
Interestingly, the atypical antidepressant bupropion (Wellbutrin), was the only antidepressant in the study that was not associated with weight gain.
Minimizing the effects of SSRIs on your weight can be difficult, as it’s common for some SSRIs to affect your appetite.
This means that you may feel hungrier after starting treatment with an SSRI, causing you to eat more and gain weight through a higher calorie intake.
A reduced appetite is also a common symptom of depression -- one that may disappear as you recover while using SSRIs. These factors can all potentially lead to weight gain.
However, there are still several steps that you can take to limit any weight gain you experience while using antidepressants:
Pay attention to your calorie intake. A study from 2009 suggests that antidepressants, including several SSRIs, don’t have any impact on your thyroid function, meaning they’re unlikely to have any major impact on your body’s metabolism. Because of this, the usual “rules” of weight gain or weight loss still apply. By focusing on your general food intake, you should be able to avoid any major unexpected weight gain (or, if your appetite decreases, weight loss) while using an SSRI.
Weigh yourself before you start taking SSRIs. This way, you’ll be able to notice changes in your weight that occur during treatment. If you notice your weight moving up or down, you can adjust your eating habits to compensate.
Exercise. Just like with many other SSRI side effects, exercise can help to keep weight gain under control. Regular exercise may also help you to recover more effectively from depression or anxiety.
If you experience significant weight loss or gain after using an SSRI, make sure to talk to your healthcare provider.
They may be able to provide additional information on what you can do to keep yourself at a healthy, optimal weight during treatment.
If you've been prescribed Prozac and are concerned about this, you can read our blog on Prozac and weight gain.
In addition to the common side effects listed above, SSRIs can cause other side effects. These may occur more frequently with some SSRIs than with others. Other side effects of SSRIs may include:
Nervousness, restlessness and agitation
Tremors or involuntary shaking
Like with other SSRI side effects, these may occur during the first few weeks of treatment and gradually disappear. If any of the side effects listed above are persistent or severe, reach out to your healthcare provider and let them know.
Just like for other side effects, they may suggest adjusting your dosage or switching to another type of antidepressant.
We have an article on switching from Lexapro to Zoloft if you'd like to learn more.
Although rare, SSRIs may cause serious side effects. SSRIs can also interact with certain other medications, potentially causing life-threatening issues.
Make sure you’re aware of the following side effects and interactions before beginning treatment with any type of SSRI.
SSRIs may contribute to an increased risk of bleeding and can interact with certain medications that prevent blood clotting, such as aspirin, warfarin (Coumadin® and other brand names) and a range of different nonsteroidal anti-inflammatory medications (NSAIDs).
When used with other medications that cause increases in serotonin, SSRIs may contribute to a potentially life-threatening condition called serotonin syndrome.
Medications that can cause serotonin syndrome when used with SSRIs include numerous other antidepressants, as well as migraine medicines called triptans.
Some herbal products, such as St. John’s wort, may also cause serotonin syndrome if used with SSRIs.
To avoid interactions while using SSRIs, make sure to inform your healthcare provider about all medications, supplements and other health products you currently or have recently used.
Read the packaging of any other medications you use to check for potential drug interaction risks.
Like all antidepressants, SSRIs come with a “black box” warning from the FDA notifying users of an increase in suicide risk for young people. SSRIs are effective at treating depression and safe for most people. However, it’s important to be aware of this risk if you are 24 or younger.
If you experience any changes in mood, suicidal thoughts or unusual behavior while undergoing treatment with an SSRI or other antidepressant, seek immediate medical assistance.
For the majority of people, SSRIs are a safe, effective form of medication for treating depression and certain anxiety disorders.
Compared to older antidepressants, they’re significantly less likely to cause side effects or potentially dangerous drug interactions.
Despite this, SSRIs can and often do cause side effects, including side effects that can interfere with your sex life. While some SSRI side effects are mild and transient, others can be persistent and frustrating to deal with.
Most of the time, SSRI side effects are treatable. If you’re prescribed an SSRI and find that side effects are starting to make your medication inconvenient or difficult to use, the best approach is always to talk to your healthcare provider about your options.
If you have depression, an anxiety disorder or another mood disorder, your healthcare provider may have mentioned SSRIs as a treatment option.
Our guide to SSRIs goes into greater detail about how these antidepressants work, their benefits, frequently asked questions and more.