Citalopram vs Sertraline: Which SSRI Is Right for You?

What Is the Difference Between Citalopram and Sertraline?

If your doctor has prescribed you citalopram or sertraline, you might be wondering: what’s the difference between them? Both belong to the SSRI family, which boost serotonin in your brain to stabilise mood. But there are important differences.

Citalopram is often described as a “cleaner” SSRI because it mostly targets serotonin alone. It can be a good choice for anxiety, but at higher doses it sometimes carries a risk of affecting heart rhythm. Sertraline, on the other hand, also nudges dopamine a little, which can help with motivation and energy. It tends to have fewer issues with the heart and fewer drug–drug interactions.

Why Would a Doctor Prescribe One Over the Other?

If you’re wondering, why have I been prescribed citalopram instead of sertraline? — the answer often comes down to your symptoms and your medical history.

Citalopram is usually favoured if your main struggle is agitation or anxiety. It has a gentler, more calming effect. Sertraline is often chosen if low energy or lack of motivation are part of the picture, because its mild dopamine activity can give you more drive.

Doctors also weigh up safety. Because citalopram can sometimes affect heart rhythm at higher doses, it may not be the first choice if you have heart disease or other risk factors. In those cases, sertraline is often the safer bet.

Will I Get Side Effects?

Like all medications, both citalopram and sertraline can cause side effects — though not everyone experiences them. Citalopram is more associated with heart-related risks, while sertraline more often causes stomach problems, like diarrhoea.

But here’s something many people don’t realise: your genes play a big role in whether you get side effects, or whether the drug even works for you at all.

Your Genes And The Future Of Prescribing SSRIs

If you’re asking yourself, Why isn’t this working for me? Why do I get side effects my friend doesn’t? — genetics is a big part of the answer. Both citalopram and sertraline are broken down in the liver by an enzyme controlled by the CYP2C19 gene. How active your version of this gene is can completely change the outcome:

• If you’re a poor metaboliser, your body clears the drug too slowly. That means higher levels in your system and more chance of side effects, like nausea or drowsiness.

• If you’re an ultra-rapid metaboliser, you clear it too fast. Even on standard doses, you may never reach a therapeutic level — the medication just doesn’t seem to help.

This isn’t just theory. Data from the UK Biobank (which links genetics to lifetime health records in 500,000 people) shows that 99.5% of individuals carry at least one genetic variant that can affect how they respond to commonly prescribed drugs, such as pain killers, cholesterol lowering medications and low mood medications. Nearly one in four participants had already been prescribed a medicine where their genetics meant an atypical response was likely.

That means this isn’t niche science — it’s mainstream. If you’re taking an SSRI, the odds are your genes are influencing how well it works for you.

Which SSRI Is “Stronger”?

People often ask, what’s the strongest SSRI? The truth is, there isn’t a single winner. Citalopram may feel stronger if your anxiety is overwhelming, while sertraline may feel stronger if you’re weighed down by fatigue and lack of motivation. The “best” choice depends on your unique biology, not just the pill itself.

Can a DNA Test for Medications Help You Decide?

Instead of relying on trial and error, pharmacogenomic (PGx) testing helps match the right SSRI to the right person. It can show whether your genes make citalopram or sertraline a better fit, whether you might need a different dose, or whether another medication altogether would be more effective.

At scale, UK Biobank is proving this approach works for whole populations. At the individual level, PGx testing can help you and your doctor make safer, more effective prescribing decisions right now.

So if you’ve ever thought: Why did my doctor pick this one? Will it work for me? Will I get side effects? — PGx testing can give you clarity, and save you from months of uncertainty.

Explore PGX for Mental Health