SSRIs For Anxiety: How They Work And What To Expect

Having constant anxiety can be debilitating and detrimental in many areas of your life. Over 40 million people¹ in the United States understand how this feels. 

Fortunately, medications can manage your anxiety and symptoms. Selective serotonin reuptake inhibitors (SSRIs) are a group of medications that may form part of your treatment plan.

What are SSRIs?

Selective serotonin reuptake inhibitors (SSRIs) are antidepressants that treat depression. However, they are also commonly prescribed for several anxiety disorders, such as social anxiety disorder, generalized anxiety disorder, obsessive-compulsive disorder, post-traumatic stress disorder, and panic disorder. They are effective in both short-term and long-term treatment².

SSRIs are the most widely prescribed antidepressant and are often the first line of pharmaceutical treatment³.

The FDA-approved⁴ SSRIs for anxiety are: 

• Citalopram (Celexa)

• Escitalopram (Lexapro)

• Fluoxetine (Prozac) 

• Paroxetine (Paxil)

• Sertraline (Zoloft)

• Fluvoxamine (Luvox)

Not all SSRIs have FDA approval for every anxiety disorder. However, even if an SSRI is not FDA-approved for an anxiety disorder, your doctor can still prescribe it off-label if they believe it’s medically appropriate and better suited to your individual needs. 

How do SSRIs work?

Serotonin is a neurotransmitter (a chemical messenger that sends signals between nerve cells in the brain.)

Serotonin stabilizes our mood, thinking, memory, sleep, and digestion. It’s one of our “happy chemicals.” 

Nerve cells naturally produce serotonin, which releases into the space between two nerve cells (the synaptic cleft). From here, it can bind to the second nerve cell (post-synaptic neuron), allowing the signal to be received. Alternatively, it can be reabsorbed and recycled through a transporter and back into the nerve cell that released it (presynaptic neuron), making it inactive. In healthy people, this process is well-balanced, so their mood remains stable. 

However, people with anxiety can have lower serotonin levels or abnormalities in the way it functions⁵. 

SSRIs prevent serotonin from being reabsorbed in the presynaptic nerve cell that produces and releases it by inhibiting the transporter that reabsorbs it. This naturally increases serotonin levels in the space between the two nerve cells, keeping it active so it can bind to the postsynaptic cell and send more signals to regulate our mood. They may also improve your response to psychological treatments. 

As SSRIs are “selective,” they don’t impact the reuptake of other neurotransmitters. 

Who should take them?

If you have chronic anxiety requiring ongoing treatment, you could consider SSRIs. They are not appropriate if you experience occasional anxiety as a natural stress response. 

How can you get them?

SSRIs are prescription medications, so you’ll need to see a medical professional such as your family doctor or a psychiatrist. They will discuss your anxiety and review your medical history to ensure SSRIs will be safe and effective for you.

The cost will depend on the specific SSRI and your dosage. Generally, the generic version costs $4-$40 per 30 days⁶, while the brand name tends to be much more expensive, costing around $329-$490 per 30 days⁶. Generics are just as effective as branded medications: They have to pass stringent FDA testing to prove they deliver the same benefits as their branded counterparts. 

How do you take them?

SSRIs are taken orally as a tablet or liquid. There are different dosages, and your doctor will usually start you on a low dose, gradually increasing it if needed. This will depend on the specific SSRI they prescribe. 

If you forget a dose, you should take it as soon as you remember to prevent withdrawal symptoms. However, if it’s very close to the time of your next dose, it is better to skip it. Taking a double dose can be dangerous as it can cause serotonin syndrome⁷, a potentially life-threatening condition. 

You can take SSRIs in the morning or at night, depending on whether they make you feel drowsy or more alert. This is very dependent on the individual, so find what works best for you. 

How long will they take to work?

SSRIs do not work immediately. Instead, you will only notice improvements in your anxiety and mood once serotonin levels have built up and normalized. Generally, it takes 2-6 weeks⁸ to feel the full effect. You might experience an initial improvement in sleep, with overall anxiety improving later. 

Even when you start feeling better, it’s important to continue taking your medication, usually for at least 6-12 months⁸ after your anxiety improves. Your doctor will tell you when you can stop taking them.

Do they cure anxiety?

Although SSRIs can reduce symptoms, they cannot cure an anxiety disorder. Low serotonin levels are not the only cause of anxiety, so others may need addressing. 

Most people will also undertake some kind of psychotherapy⁹ (talk therapy), such as cognitive behavior therapy. Studies have shown that psychotherapy amplifies the effectiveness of SSRIs and helps patients overcome the mental challenges associated with anxiety disorders.

Which SSRI should I take?

The different types of SSRIs all work in the same way: Increasing serotonin levels in the brain. They differ in how potent they are, how much they interact with other medications, their side effects, and how fast the body eliminates the drug. 

Here are some key differences:

Citalopram (Celexa)

• Usually prescribed for generalized anxiety disorder (GAD)

• More likely to cause an overdose

• More likely to cause cardiac-related side effects, such as long QT syndrome¹⁰

• Has fewer interactions with¹¹ other drugs 

Escitalopram (Lexapro)

• Usually prescribed for generalized anxiety disorder

• More likely to cause an overdose

• More likely to cause cardiac-related side effects, such as long QT syndrome 

• Has fewer side effects overall, so it may be more tolerable 

Paroxetine (Paxil)

• Usually prescribed for generalized anxiety disorder, panic disorder, obsessive-compulsive disorder (OCD), and social anxiety disorder 

• May cause cardiovascular congenital disabilities in pregnant women. Due to this, the FDA updated paroxetine from Category C¹² (suspected to cause fetal damage) to Category D (evidence of human fetal risk). 

• Has more interactions with other drugs 

• Tends to have a greater sedative effect 

• More likely to cause weight gain 

Sertraline (Zoloft)

• Usually prescribed for OCD, PTSD, panic disorder, and social anxiety disorder

• Generally a safer option for pregnant and breastfeeding women

• Is more effective at a higher dose¹¹

Fluoxetine (Prozac)

• Usually prescribed for OCD and panic disorder 

• Generally safest for people under the age of 18

• Has more interactions with other drugs 

• Most likely to cause weight loss and agitation 

• Causes the least withdrawal symptoms 

• A safer option for pregnant women 

Fluvoxamine (Luvox)

• Only prescribed for OCD 

• More likely to cause gastrointestinal-related side effects 

Side effects

Like all medications, SSRIs can have side effects.

Some side effects may mimic your anxiety symptoms or even make you feel worse initially. You may think the treatment isn’t working, but this usually passes as long as you continue with the treatment. 

Minor side effects include: 

• Digestive problems: Diarrhea or constipation and loss or gain of appetite 

• Sexual dysfunction: Low sex drive, erectile issues, or inability to orgasm

• Sleep issues: Drowsiness or insomnia

• Anxiety symptoms: Agitation and shakiness 

• Physical changes: Blurred vision, dizziness, dry mouth, nausea 

These side effects are relatively common, with 38% of people¹³ experiencing at least one. They typically subside after a few weeks of taking the drug. You may need to switch your medication or reduce your dose if symptoms persist. 

There are a few rare but serious side effects you need to be aware of. If you experience any of them, seek immediate medical attention as they can be life-threatening. 

Low sodium levels in the blood

This is especially troublesome in the elderly. Mild symptoms are similar to SSRI side effects, but more severe symptoms include disorientation, muscle weakness, confusion, and coma. 

Self-harm and suicidal thoughts or behaviors

People under the age of 25 are most likely to experience this, particularly in the first three weeks of beginning the drug or changing the dosage. It may be helpful to let a friend or family member know that you are taking SSRIs. They will be able to keep an eye on you and watch out for any concerning signs. These include aggressive or hostile behavior, withdrawal from friends and family, and increased suicidal statements. 

Serotonin syndrome

This occurs when the serotonin levels in your brain become too high. Mild to moderate symptoms include confusion, rapid heart rate, dilated pupils, twitching muscles, sweating, and shivering. People experience fever, seizures, irregular heartbeat, and unconsciousness in severe cases. 

Serotonin syndrome is rare. Usually, it only occurs if you increase your dose or you’re simultaneously taking other medications that increase serotonin, such as St. John’s Wort. 

Despite these potential side effects, SSRIs have fewer side effects¹⁴ than other anxiety medications since they are selective for serotonin and do not impact other neurotransmitters. 

Talk to your doctor if you experience any side effects, even if you think they are minor. 

What happens when you want to stop taking SSRIs?

Similar to how you need to progressively increase your dose of SSRIs, you need to gradually decrease it when you want to stop taking them. You will usually reduce your medication over at least two weeks¹¹.

SSRIs are not addictive, and most people do not become dependent⁸ on them. However, if you suddenly stop taking SSRIs, it can cause “discontinuation syndrome”¹⁵ or a return of your anxiety. 

Discontinuation syndrome can cause withdrawal-like symptoms, such as: 

• Anxiety

• Dizziness

• Electric sensations

• Seizures

• Stomach ache

• Flu-like symptoms 

Who should not take SSRIs?

SSRIs are safe for most people. However, some medical conditions can increase the risk of serious side effects from SSRIs. If any of the following apply, let your doctor know before starting medication: 

• Being in a manic phase of bipolar disorder 

• Bleeding disorders

• Diabetes 

• Uncontrolled epilepsy

• Kidney, liver, or heart conditions 

• Pregnancy¹⁶: due to the risk of heart and lung defects or miscarriage in the first trimester 

• Breastfeeding

• Being under age 25 (However, some studies show SSRIs are still safe and effective when doctors monitor patients for suicidal behaviors and thoughts.) 

In addition, SSRIs negatively interact with some medications. These include, but are not limited to:  

• NSAIDs (painkillers such as ibuprofen and naproxen)

• Antiplatelets such as aspirin 

• Lithium

• Other antidepressants (such as monoamine oxidase inhibitors or SNRIs)

• Any other medication that increases serotonin levels (such as the herbal remedy St. John’s Wort) 

This is not a definitive list. Even if you don’t have any of these conditions, SSRIs may still be unsuitable based on your medical history. Likewise, having one of these conditions does not necessarily mean that you cannot try SSRIs. It may just mean your doctor needs to carefully select your SSRI, the dosage, and monitor you closely for side effects. 

Some other circumstances to be aware of include: 

• Since SSRIs can make you feel drowsy, avoid driving after taking your medication. 

• Avoid drinking alcohol after taking your medication. This combination can impair your judgment, motor skills, coordination, and cause drowsiness. As alcohol is a depressant, it can also decrease SSRIs’ effectiveness. 

• The SSRI fluvoxamine can enhance the effects of caffeine, so it could cause symptoms such as heart palpitations or insomnia. 

The lowdown

If you are struggling with anxiety or think you may have an anxiety disorder, it is important to seek help from a medical professional. 

Medications such as SSRIs could be an effective component of your treatment plan, but they should not be a substitute for psychotherapy and lifestyle changes.