SSRI Side Effects: Everything You Need to Know

What Are SSRIs?

Selective serotonin reuptake inhibitors, or SSRIs, are a group of medications commonly used to treat anxiety, depression, and other psychiatric conditions.¹ They act by affecting levels of serotonin in the body, a body chemical that promotes happiness, sleep, memory, and hunger.

Common SSRIs include Prozac (fluoxetine), Lexapro (escitalopram), Celexa (citalopram), and Paxil (paroxetine). ¹ When SSRIs increase the amount of serotonin around nerve cells, they gradually increase the amount of serotonin our brains produce over time. As a result, it can take 1-2 weeks for SSRIs to begin working, and up to 4-6 weeks for them to take full effect.

Side Effects of SSRIs

SSRIs work by increasing serotonin levels in the brain and body, and for some people, this change can cause side effects. During the first  1-2 weeks of taking an SSRI, the brain begins to get used to the increase in serotonin, which is when side effects may become noticeable. Some side effects can be common and mild, often needing no medical care. Others can be severe or rare, typically needing immediate medical attention.

Common Side Effects of SSRIs

Some individuals may experience common antidepressant side effects at first while their body gets used to the medication.¹ Mild symptoms, such as lowered mood and motivation, are common and usually do not require medical attention.

Common side effects of SSRIs can include:^2,3,4,5,6

• Headache
• Dizziness
• Nausea or vomiting
• Erectile dysfunction or anorgasmia (difficulty having an orgasm)
• A flat, red, and itchy rash
• Insomnia
• Agitation
• Increased or decreased appetite
• Fatigue
• Drowsiness

Severe Side Effects of SSRIs

Despite the rigorous testing to ensure SSRIs meet their desired effects, you may still develop unwanted effects, some of which may require immediate medical attention to prevent further harm to the person taking SSRIs. Although severe side effects are considered rare, they can happen to anyone taking an SSRI or when SSRIs are combined with other antidepressants or when doses are decreased too quickly.¹

Severe side effects of SSRIs can include:^2,3,4,5,6

• Serotonin syndrome: When there is too much serotonin in the body, symptoms occur such as shaking, fever, sweating, fast or irregular heartbeat, and loss of muscle function.
• Increased suicide risks: SSRIs are linked with increased risk of suicidal thinking and behavior in children, adolescents, and adults 24 and younger.   Though these side effects are uncommon, watch for signs of agitation, irritability, and unusual changes in behavior. SSRIs have a black box warning, the most serious kind of warning, for this risk.
• Antidepressant withdrawal: If you suddenly stop or drastically decrease your dose of an SSRI that you have been taking for several months, you may experience antidepressant withdrawal. Symptoms may include nausea, irritability or agitation, flu-like symptoms (body aches, sweating, lethargy), headache, and dizziness.
• Worsened anxiety symptoms: From the initial decrease in serotonin, SSRIs may worsen anxiety at first. Symptoms of worsening anxiety symptoms include easily irritated, brain fog, heart palpitations, body tension, fatigue, eating more or less than usual, and nausea.
• Seizures: Though uncommon, SSRIs can lower the amount of sodium in your body and put you at risk of having seizures.
• Confusion and cognitive impairment: Also, due to lowered sodium levels, SSRIs may impair cognitive function.
• Abnormal bleeding: SSRIs may increase your risk of bleeding.
• Allergic or anaphylaxis reaction: You may be allergic to SSRIs and experience trouble breathing, swelling, or hives.
• Severe muscle or stomach pain: A rare but severe side effect of SSRIs includes muscle breakdown that causes pain. Also, you may experience stomach pain either with nausea and vomiting or from bleeding within the digestive system.

Rare Side Effects of SSRIs

While the above side effects have been studied and have an understood prevalence, there are rare or uncommon side effects that have been reported outside of clinical trials and it is unclear if they are related to SSRIs.¹ The majority of these side effects are serious. If you are experiencing any of the list below, you should seek immediate medical attention.

Rare side effects of SSRIs that have been reported and may need immediate medical attention include:^2,3,4,5,6

• Pupil dilation
• Paralysis of one or multiple muscles
• Muscle/stomach pain
• Fainting
• Electric shock sensation during urination
• Agitation
• Dizziness
• Severe nausea and vomiting
• Increased body temperature and flushing
• Increased blood pressure and heart rate
• Delirium
• Hallucinations
• Tremor, rigidity, and seizures
• Coma
• Death

Rare side effects of SSRIs that have been reported and do not require immediate medical attention:

• Excess breast milk
• Swollen glands
• Mild nausea or vomiting

If you think you are experiencing any of these side effects from your medication, you should talk with your prescriber or seek medical care immediately. Side effects are different for everyone, and this list may not include every potential side effect. Speak with your prescriber to ensure that you know all the potential side effects before taking the medication.

Allergic Reactions to SSRIs

Serious reactions to SSRIs are rare, but you may be allergic to SSRIs if you have a history of allergic reactions to antidepressants or other medications, or are allergic to an ingredient in the medication.¹ Mild allergic reactions to SSRIs, such as a flat, red, and itching rash, are common and may improve with an over-the-counter treatment put directly on the skin.

Serious allergic reactions to SSRIs can include:

• Breathing trouble or wheezing
• Swelling
• Hives
• Clammy skin
• Confusion
• Fast or irregular heart rate
• Dizziness
• Loss of consciousness

If you experience any of these allergic reactions, you should have someone drive you to the nearest emergency room immediately. You may be allergic to other SSRIs but not necessarily all of them. If you did not have a severe reaction, it is likely safe to try other SSRIs.

Long-Term Side Effects of SSRIs

Side effects from SSRIs may go away after 4-8 weeks or may persist for months or years.¹ The side effects typically last while your body gets used to the medication and can be physical or psychological. You may be able to reduce the occurrence of long-term effects by switching medications or reducing your dose. The likelihood of developing some long-term side effects is higher than others, but SSRIs are generally considered safe to use.

Long-term side effects of SSRI use may include:^2,3,4,5,6

• Sexual problems: Serotonin may affect other hormones and cause sexual problems that may emerge as long-term side effects. If you have tried all of the SSRIs and are still having issues, you should ask your doctor about trying bupropion, a medication that may help with anxiety or depression without causing sexual issues.
• Feeling emotionally numb: SSRIs may affect levels of dopamine, lowering your response to emotions, which can last months to years. However, certain SSRIs, like escitalopram or fluoxetine, may stimulate dopamine more and may be better choices.
• Nausea and Vomiting: Nausea may persist for up to 3 months while your body adjusts to the medication. If the nausea is intolerable, ask your doctor about trying another SSRI.
• Weight changes: Due to the nature of antidepressants, as you begin to feel better, you may gain or lose a noticeable amount of weight after a few weeks or months.
• Cognitive impairment: SSRIs may interfere with thought processing for the first 2-4 weeks or for longer. 

Substances and Medications That Can Have Adverse Interactions with SSRIs

Certain substances and medications should be avoided while taking SSRIs, as they can risk serotonin syndrome, a rare but serious side effect. Also, SSRIs are metabolized by the same enzymes as some substances and medications and can increase other substances’ absorption. There may also be interactions with SSRIs and other substances having similar effects on the body, leading to side effects.

Substances you may need to avoid using while on SSRIs include:^2,3,4,5,6

• Alcohol: Alcohol and SSRIs together may risk seizures and bleeding within the digestive system.
• Grapefruit: Grapefruit inhibits a major enzyme that is used to break down SSRIs and can result in increased levels of serotonin.
• St John’s Wort: St John’s wort may act as strongly as other antidepressants. Therefore, it is highly recommended to not take it with SSRIs.
• Tryptophan: Large amounts of foods high in tryptophan, such as aged cheese, beer, and chocolate, can increase the risk of serotonin syndrome.
• Caffeine: Fluvoxamine should not be taken with large amounts of caffeine, as it can enhance its effects and may make you feel dizzy, sick, or restless and cause heart palpitations.
• Garlic, ginkgo, and ginger: Large amounts of these three G’s can increase your risk of bleeding, especially when combined with SSRIs.
• Potassium: Potassium helps lower sodium levels, which SSRIs may contribute to, leading to seizures.

Medications you should avoid using while on SSRIs include:^2,3,4,5,6

• Migraine medications: Triptans can increase serotonin, risking serotonin syndrome if taken with an SSRI.
• Monoamine oxidase inhibitors (MAOIs): Taking SSRIs with MAOIs, another type of antidepressant, may increase the risk of serotonin syndrome. These medications should not be taken together until MAOIs have been discontinued for 14 days.
• Other SSRIs: A combination of SSRIs has the potential to cause serotonin syndrome.
• Serotonin Norepinephrine Reuptake Inhibitors (SNRIs): SNRIs, such as Cymbalta and Effexor, also act on serotonin receptors, increasing the risk of serotonin syndrome and other side effects.
• Tricyclic Antidepressants (TCAs): Both TCAs and SSRIs increase serotonin levels, risking serotonin syndrome.
• Antipsychotics: SSRIs can elevate the level of some antipsychotic medications in the blood, risking sedation and lowering white blood cell levels.
• Anticonvulsants: Phenytoin and carbamazepine levels are elevated by SSRIs, risking lowered sodium levels, and therefore seizures and death.
• Benzodiazepines: SSRIs and benzodiazepines may impact movement and cognitive function.
• Opioids and tramadol: SSRIs can increase the absorption of opioids and tramadol, causing an increased risk of confusion, dizziness, and interference with breathing.
• NSAIDs: Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used over-the-counter pain medications. Using NSAIDs and SSRIs together may increase the risk of bleeding.
• Pimozide and thioridazine: SSRIs should not be used with pimozide or thioridazine due to the risk of irregular heart rate.

Disclaimer: Taking certain medications, herbs, or supplements alongside SSRIs can change how SSRIs works in your body or increase the risk for serious side effects. This article does not consider all the possible interactions. Please let your doctor, psychiatrists, and pharmacists know about all the products you currently use, such as prescription medication, nonprescription drugs, and herbal supplements. Do not start, stop, or change the dosage of any medicines without your doctor’s approval.

Who Experiences the Most Side Effects?

It’s important to speak with your doctor about your health conditions before taking SSRIs. Certain health conditions, like currently having issues that SSRIs commonly cause, can increase the likelihood of developing side effects. ¹ The most common side effects of SSRIs include headaches, nausea, and sexual dysfunction. Also, patients with a history of suicidal ideation are more likely to experience suicidal ideation and should only take SSRIs if the benefit outweighs the risk.

Here is how SSRI side effects may impact people differently:

SSRI Side Effects in Women

Because serotonin acts as a hormone in the body, women may commonly experience certain side effects. SSRIs in women may cause headaches, difficulty with sex drive, or delayed or absent orgasms. If you experience these side effects, ask your doctor to try a different SSRI.

Because heart malformations can form in the fetus in the first trimester, SSRIs should only be used in pregnancy if the benefits outweigh the risks. Consider tapering in pregnant women during the third trimester because infants are at risk of developing persistent pulmonary hypertension. Some SSRIs are excreted in breast milk in small amounts and may cause mild to moderate side effects, so nursing while taking certain SSRIs is not recommended.

SSRI Side Effects in Men

Common side effects from SSRIs that may occur in men include difficulty getting or maintaining an erection and difficulty ejaculating. Similarly to women, you should try another SSRI if the side effects are impactful, or other medications may be taken that do not have these side effects.

SSRI Side Effects in Children and Older Adults

Children may take certain SSRIs, such as fluoxetine.⁴ Side effects that are more likely to occur in children include the risk of suicidal ideation. Because fluoxetine stays in the body in children longer than adults, children may be more susceptible to side effects and may need a dosing schedule that is less frequent.

Also, the elderly may be more at risk of experiencing side effects from lowered sodium levels, resulting in headaches, confusion, cognitive impairment, and seizures. The consideration of SSRIs in the elderly is important since the elderly are more at risk of having falls. In addition, SSRIs are metabolized by the liver and should not be taken with significant liver impairment.

Withdrawal Symptoms from SSRIs

Patients discontinuing SSRIs should be titrated down off of doses and should not immediately stop taking these unless instructed otherwise by their physician or pharmacist.¹ Patients taking SSRIs can develop a physical dependency, even without abuse. Physical dependency is the physiological symptoms that occur when a drug is stopped, while abuse is the misuse of a medication despite its negative effects.

If you stopped an SSRI suddenly, you may experience antidepressant withdrawal symptoms.¹ Withdrawal symptoms include dizziness, fatigue, headache, nausea, flu-like symptoms, insomnia, anxiety, irritability, and agitation. Symptoms may occur within 2-4 days and may last 1-2 weeks. If you feel that you are experiencing physical dependence, you should talk to your doctor about starting another antidepressant with less risk. A therapist, antidepressant withdrawal support group, and exercise may also help with symptoms of anxiety and depression.

Questions to Ask Your Health Team About SSRI Side Effects

If you have anxiety or depression, the first medication your doctor will likely try is an SSRI. These medications may commonly have side effects like headaches, nausea, or sexual problems. If you experience issues or a mild allergic reaction, it can be frustrating but ask your doctor to keep trying other SSRIs until you find one that works for you.

Questions to ask your care team when considering the side effects of SSRIs are:

• How long can SSRI side effects last?
• Am I at risk for more severe symptoms if I am already taking other anxiety/depression medications?
• What is the best dosage to ensure fewer side effects?
• Are there drugs I am taking that could have negative interactions?
• When should I reach out to you if I am experiencing side effects?
• Is there anything I should tell my therapist about this new medication?
• What dose will I expect to experience more serious side effects?
• How can I prevent side effects from occurring?
• What supplements should I avoid while taking SSRIs?
• What side effects is my child more likely to experience?
• How can I help monitor my child for severe side effects?
• May I take this medication during pregnancy?
• When should I stop taking this medicine?
• May I take this medication while breastfeeding?

In My Experience

In my experience, patients generally tolerate SSRIs well. They may have some side effects that last during the initial phase, but then are able to stay on the medication for as long as needed. It’s important to talk to your doctor about this topic and follow their guidance because SSRIs may come with some serious side effects if not taken correctly.

For Further Reading

• How to Get Antidepressants: Everything You Need to Know
• How Do Antidepressants Make You Feel? Possible Side Effects & Changes
• How Long Does it Take for Antidepressants to Work?
• Trintellix Side Effects: Common, Severe, & Warnings
• Trintellix (Vortioxetine): Uses, Dosage, Side Effects, & Warnings
• Anxiety and Depression Association of America