Citalopram typically makes you feel worse before it makes you feel better. During the first one to two weeks, most people notice side effects like nausea, drowsiness, or heightened anxiety before any mood improvement kicks in. The antidepressant benefits usually take four to six weeks to fully develop, which means there’s an uncomfortable gap where you’re dealing with new physical sensations without yet feeling the payoff.
Why Side Effects Come Before Relief
Citalopram works by blocking the brain’s reabsorption of serotonin, leaving more of it available between nerve cells. This change in serotonin levels starts happening almost immediately after your first dose. But here’s the catch: your brain needs weeks to adapt to this new chemical environment before your mood actually lifts. The side effects you feel in the first few days are your body reacting to a sudden shift in serotonin activity, while the therapeutic benefits require longer-term changes in how your brain’s signaling pathways function.
Some people notice small improvements in sleep or energy within one to two weeks. But for most, the full antidepressant effect takes four to six weeks to settle in. That’s why it’s important not to judge the medication based on how the first week or two feels.
What the First Two Weeks Typically Feel Like
The most common early sensation is nausea. In clinical trials, about 21% of people taking citalopram reported nausea, compared to 13% on a placebo. It tends to be mild and often fades after the first week or two. Some people find that taking the medication with food helps.
Drowsiness is another frequent early experience. You might feel unusually tired during the day, foggy, or like you need more sleep than normal. On the flip side, some people experience the opposite: difficulty falling or staying asleep, which showed up in about 19% of trial participants (though the placebo group reported nearly identical rates, suggesting some of that insomnia comes from the underlying condition rather than the drug itself).
Other common early sensations include dry mouth, increased sweating, and changes in appetite. Sexual side effects, including reduced sex drive and difficulty reaching orgasm, can also begin early and are among the more persistent complaints. These side effects are generally described as mild to moderate and are most noticeable during the first one to two weeks before tapering off.
The Temporary Spike in Anxiety
One of the more unsettling early experiences is a temporary increase in anxiety. If you’re taking citalopram for panic disorder or generalized anxiety, this can feel counterintuitive and alarming. Your anxiety may actually get worse during the first few weeks before the medication begins to calm things down. The NHS specifically notes that this paradoxical anxiety “usually wears off after a few weeks.”
This jittery, restless feeling sometimes comes with agitation, racing thoughts, or a sense of being “wired.” It doesn’t mean the medication isn’t working or that it’s the wrong one for you. It means your brain is in an adjustment period where serotonin levels are elevated but the downstream calming effects haven’t caught up yet. Some people describe it as feeling like they’ve had too much caffeine.
Feeling Worse Before Feeling Better
The NHS puts it plainly: “Some people feel worse during the first few weeks of treatment before they begin to feel better.” This is one of the most important things to know going in, because it’s the point where many people are tempted to stop. The general advice is to give citalopram at least six weeks before deciding whether it’s effective.
During this adjustment window, you might also notice mood swings, irritability, or unusual emotional reactions that feel out of character. These are recognized effects of the early treatment phase. The FDA’s prescribing information specifically calls out the first few months of treatment, and especially dose changes, as a period requiring close monitoring for worsening mood, agitation, or new emotional symptoms. This is particularly relevant for younger adults under 25.
Emotional Numbness Can Develop Later
Some people taking citalopram eventually report a blunted emotional range, where both positive and negative feelings seem muted. This isn’t usually an immediate first-week experience. Research suggests it tends to emerge with a slight delay, sometimes weeks or months into treatment, which can make it harder to connect to the medication. The typical pattern is that depression improves first, but over time emotions in general feel flattened. If you notice you’ve stopped feeling much of anything, not just sadness but also joy or excitement, that’s worth raising with your prescriber.
Practical Tips for the First Few Weeks
Most adults start at 20 mg once daily. This starting dose is intentionally conservative to give your body time to adjust. Taking the medication at a consistent time each day matters more than the specific hour, but if you’re having trouble sleeping, taking it in the morning is a reasonable strategy. It can be taken with or without food, though pairing it with a meal may help if nausea is an issue.
The adjustment period is genuinely uncomfortable for some people, but the side effects that show up in the first two weeks are usually the ones that fade fastest. Nausea, headaches, and that initial spike in anxiety tend to resolve on their own as your body adapts. Sexual side effects and drowsiness can be more stubborn. Keeping a brief daily note of how you feel, even just a few words, can help you spot genuine trends rather than reacting to day-to-day fluctuations. It also gives you something concrete to share at follow-up appointments.