Celexa vs. Zoloft: similarities and differences

Whether you’re considering starting treatment with an SSRI antidepressant, or if you’ve been taking one for a while, you may be wondering if you’re taking the best drug for you. As you read about the similarities and differences between SSRIs, keep two key things in mind: all SSRIs take several weeks to start working, and individual results can vary. 

Read on to learn more about two SSRIs: Celexa and Zoloft.

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Celexa (citalopram) and Zoloft (sertraline) are antidepressant medications known as selective serotonin reuptake inhibitors (SSRIs). They’re only available with a prescription from your healthcare provider.

Our bodies naturally make serotonin, the “feel-good hormone.” Serotonin acts as a chemical messenger that communicates signals from one brain cell to another. These signals play a major role in many brain functions, including mood, appetite, fear, sleep, and sexual behavior (Sahli, 2016). Depression is thought to be associated with low levels of serotonin. 

SSRIs work by blocking the absorption of serotonin into cells, increasing the amount available. Decades of clinical studies show that SSRIs can be an effective part of treating depression and anxiety disorders, especially when used in combination with therapy and lifestyle changes.

The Food and Drug Administration (FDA) has issued a warning that antidepressant medications, including SSRIs, may increase the risk of suicidal thoughts and behaviors, mainly in children, teens, and young adults up to age 25. Because of this, healthcare providers will monitor SSRI treatment in this age group carefully, especially when the drug is first started or after the dose increases (Chu, 2021). 

If you’re starting treatment with Celexa or Zoloft, it’s important to know that neither of these drugs starts working immediately. Taken once a day, it takes at least two weeks before SSRIs begin making a noticeable difference for most people. It can take up to four to six weeks for SSRIs to reach their full level of effectiveness. Because of this, it’s best to take your medication every day, around the same time each day, without skipping doses, as instructed by your healthcare provider (Chu, 2021).

Celexa is the brand-name version of the generic drug citalopram. It was FDA-approved in 1998. Celexa comes in two forms: an oral tablet (10 mg, 20 mg, and 40 mg) and an oral liquid solution (10 mg/5 mL) (Allergan, 2019). 

Zoloft is the brand name of the generic drug sertraline, and the FDA originally approved it in 1991. It comes in two forms: an oral tablet (25 mg, 50 mg, and 100 mg) and an oral liquid solution (20 mg/mL). Zoloft is usually taken once a day (Pfizer, 2016).

While Celexa and Zoloft work similarly, the FDA approves them for different conditions.

Celexa

The FDA-approved uses of Celexa in adults include (Allergan, 2019):

• Major depressive disorder (MDD)

Off-label (not FDA-approved) uses for Celexa include (Sharbaf Shoar, 2021):

• Obsessive-compulsive disorder (OCD)

• Panic disorder

• Generalized anxiety disorder (GAD)

• Social anxiety disorder (SAD)

• Separation anxiety disorder 

• Premenstrual dysphoric disorder (PMDD)

Zoloft

Zoloft’s FDA-approved uses in adults (and children when age is specified) include (Pfizer, 2016):

• Major depressive disorder (MDD)

• Obsessive-compulsive disorder (OCD) (age six years and older)

• Panic disorder (PD)

• Post-traumatic stress disorder (PTSD)

• Social anxiety disorder (SAD)

• Premenstrual dysphoric disorder (PMDD)

Off-label (not FDA-approved) uses for Zoloft include (Singh, 2020):

• Generalized anxiety disorder (GAD)

• Binge eating disorder

• Body dysmorphic disorder

• Bulimia nervosa

Like all medications, Celexa or Zoloft can cause mild or severe adverse effects. To minimize the risk of side effects, your healthcare provider may recommend starting with a lower dose of Celexa or Zoloft. Then, after at least one week, it’s common that they’ll increase your dosage. This approach helps your body adjust to taking a new medication (Pfizer, 2016; Allergan, 2019). 

For most people, some common side effects of Celexa and Zoloft, such as nausea, tend to go away on their own after the first few weeks of treatment (Kelly, 2008).

The following section lists the most common side effects of Celexa and Zoloft. These lists do not include all of the possible side effects. Not everyone who takes Celexa or Zoloft develops side effects.

Celexa side effects

The only side effect reported in at least 5 % of participants who took Celexa in clinical studies was ejaculation problems (such as delayed ejaculation) in those assigned male sex at birth (Allergan, 2019).

Other possible side effects of Celexa include (Allergan, 2019):

• Nausea

• Sleepiness

• Weakness

• Dizziness

• Nervousness

• Insomnia

• Sexual problems (see next section for details)

• Sweating

• Shaking

• Not feeling hungry

• Dry mouth

• Constipation

• Diarrhea

• Respiratory infections

• Yawning

Zoloft side effects

The most common side effects of Zoloft include (Pfizer, 2016):

• Nausea

• Diarrhea or loose stool

• Indigestion

• Reduced hunger

• Shaking

• Increased sweating

• Sexual problems (see next section for details)

Sexual side effects

Sexual side effects can happen with all SSRIs, and some are more common if you take a high dose. If you’re experiencing sexual side effects, it’s important to talk with your healthcare provider. They might adjust your dosage, change your medication, or suggest treatment options such as Viagra (sildenafil) to help you (Jing, 2016).

Sexual side effects that are most common with Celexa include (Allergan, 2019):

• Ejaculation problems such as delayed ejaculation

• Decreased sex drive

• Impotence, which can include erectile dysfunction or difficulty reaching orgasm 

Zoloft’s most common sexual side effects are (Pfizer, 2016):

• Failure to ejaculate

• Decreased sex drive

Withdrawal symptoms

If you and your healthcare provider decide that you should stop taking Celexa or Zoloft, they’ll instruct you on how to gradually reduce your dose before stopping. Suddenly stopping these medications can cause side effects known as withdrawal symptoms.

The most common withdrawal symptoms include nausea, vomiting, diarrhea, headache, light-headedness, dizziness, loss of appetite, sweating, drowsiness, chills, shaking, lack of energy, and trouble sleeping (Sharbaf Shoar, 2021). 

Some medications can interact with SSRIs. If you’re taking Celexa or Zoloft, it's essential to consult your pharmacist or healthcare provider before taking any new medications, including over-the-counter drugs or dietary supplements.

Bleeding risk

The combination of SSRIs with certain medications can increase the risk of bleeding. This can cause bruising easily, excessive nosebleeds, injuries that take a long time to stop bleeding, or severe stomach ulcers or bleeding. To avoid this, it’s best to avoid medications known to make blood thinner while taking SSRIs. Some examples to avoid include:

• Aspirin

• Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn)

• Anticoagulant drugs, commonly called blood-thinners, such as warfarin (Coumadin)

• Antiplatelet drugs, such as clopidogrel (Plavix)

Serotonin syndrome

Serotonin syndrome is a rare but serious risk that comes with SSRIs, but combining certain drugs can further increase this risk. SSRIs work by increasing the availability of serotonin in your brain. However, if serotonin levels become too high, you could develop serotonin syndrome, ranging from mild to life-threatening. Symptoms of serotonin syndrome include nausea, vomiting, excess sweating, dizziness, changes in heart rate or blood pressure, increased body temperature, tremor, muscle stiffness, or seizures. 

Several types of medications increase the risk of serotonin syndrome and should generally be avoided with SSRIs, such as (Pfizer, 2016):

• Other types of antidepressants, including tricyclic antidepressants such as amitriptyline (Elavil)

• Buspirone (Buspar)

• Amphetamines, such as Adderall

• Triptans, such as sumatriptan (Imitrex) 

• Fentanyl (Duragesic)

• Lithium

• Tramadol (Ultram)

• St. John’s Wort, an herbal remedy that’s advertised to support mental health

• Monoamine oxidase inhibitors (MAOIs), such as linezolid (Zyvox). You must wait at least 14 days after stopping an MAOI to start any SSRI (and vice-versa).

Heart arrhythmias

When certain drugs are combined, they increase the risk of a rare but serious heart rhythm problem known as QT-prolongation. All SSRIs carry a risk of affecting the electrical activity in your heart, but this risk is higher with Celexa. Because of this risk, certain drugs shouldn’t be combined with Celexa, particularly if you are taking a high dose (20 mg or more per day). Some examples include (Allergan, 2019):

• Certain heart medications, such as amiodarone (Cordarone) and sotalol (Betapace)

• Antipsychotic drugs, such as pimozide (Orap)

• Fluoroquinolone antibiotics, such as ciprofloxacin (Cipro) and moxifloxacin (Avelox)

• Methadone (Dolophine)

If your healthcare provider deems it medically necessary for you to take any of these medications with Celexa, they’ll monitor your heart more carefully. Be sure to let your healthcare provider know right away if you develop dizziness, light-headedness, or heart palpitations. 

We’ve given you a lot of information regarding the differences and similarities between these two SSRIs medications. Here is a summary:

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

July 26, 2021

Written by

Patricia Weiser, PharmD

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.