COVID-19 can affect how your antidepressants work in several ways. The infection itself triggers inflammation that slows your body’s ability to break down many medications, potentially raising drug levels in your bloodstream. COVID treatments like Paxlovid can cause significant interactions with specific antidepressants. And for people who develop long COVID, persistent inflammation may make depression harder to treat with standard medications. Here’s what each of those looks like in practice.
How the Infection Changes Drug Metabolism
Your liver relies on a family of enzymes to process roughly 75% of all medications, including most antidepressants. When COVID-19 triggers a strong immune response, the inflammatory molecules your body releases, particularly IL-6 and TNF-alpha, suppress the activity of these enzymes. The result: your liver clears drugs more slowly than usual, and blood levels of those medications can climb higher than expected.
This isn’t unique to COVID. Any serious infection or inflammatory state can do the same thing. But COVID-19 is notable for the intensity and duration of the inflammatory response it produces in many people. If you’re taking a stable dose of an antidepressant and suddenly feel more side effects during an active infection (dizziness, nausea, excessive drowsiness), this enzyme suppression is a plausible explanation. The effect generally reverses as the infection clears and inflammation subsides.
Paxlovid Interactions With Antidepressants
The bigger and more immediate concern for most people is Paxlovid, the antiviral commonly prescribed for COVID-19. Paxlovid contains ritonavir, a powerful enzyme inhibitor that dramatically changes how your body processes certain drugs. If you’re prescribed Paxlovid while taking an antidepressant, the interaction depends on which one you take.
Trazodone is the most concerning combination. Ritonavir blocks the enzyme that clears trazodone, causing its levels to rise substantially. This can lead to nausea, dizziness, dangerously low blood pressure, and fainting. The FDA prescribing information flags this as a significant interaction requiring a lower trazodone dose.
Mirtazapine levels also increase when taken with Paxlovid through the same mechanism. This raises the risk of excessive sedation and other side effects, and dose adjustment may be needed.
Bupropion goes the opposite direction. Ritonavir speeds up bupropion’s breakdown, lowering its levels in your blood. This could make the medication less effective during the treatment course.
Desvenlafaxine concentrations may rise with Paxlovid use, though the interaction is considered less severe. Most common SSRIs like sertraline and fluoxetine are not flagged as major Paxlovid interactions, but individual responses vary. If you’re prescribed Paxlovid, make sure whoever prescribes it knows exactly which antidepressant you take and at what dose.
Serotonin Syndrome Risk
In rare cases, Paxlovid’s enzyme-blocking effects can push serotonin-related drugs to toxic levels, triggering serotonin syndrome. This is a potentially dangerous condition marked by tremors, confusion, rapid heart rate, excessive sweating, and involuntary eye movements. One documented case involved a woman in her early 40s who developed serotonin syndrome two days after starting Paxlovid while taking buspirone and other serotonergic medications.
Serotonin syndrome from Paxlovid remains rare, but the risk is real if you take multiple medications that raise serotonin activity. The mechanism is straightforward: ritonavir prevents your body from clearing these drugs at its normal rate, so their combined effect intensifies. If you develop tremors, confusion, or profuse sweating shortly after starting Paxlovid, those symptoms need urgent medical attention.
COVID’s Effect on Serotonin Itself
Beyond drug metabolism, COVID-19 appears to directly reduce your body’s serotonin supply. Research published in Cell found that viral infection lowers serotonin through three separate pathways: it reduces intestinal absorption of tryptophan (the raw material your body uses to make serotonin), it depletes the platelets that store serotonin, and it accelerates serotonin breakdown.
During a short-lived infection, serotonin levels typically bounce back to normal after the virus clears. But in people with persistent viral remnants or ongoing inflammation, the reduction can be sustained. This matters for anyone taking an SSRI, because these medications work by keeping existing serotonin active longer. If your body is producing less serotonin to begin with, the medication has less to work with. You might notice your antidepressant feels less effective during and shortly after a COVID infection, even at the same dose.
Long COVID and Treatment-Resistant Depression
The most significant long-term concern is for people who develop long COVID. A study of COVID survivors found that 40% of those who developed major depression after their infection met criteria for treatment-resistant depression, meaning standard antidepressants weren’t adequately controlling their symptoms. That’s a strikingly high rate.
The driving factor appears to be persistent inflammation. People who had higher levels of inflammatory molecules during their initial COVID hospitalization were more likely to develop new-onset depression afterward, and more likely to have depression that didn’t respond well to conventional treatment. High IL-6 levels in particular have been linked to worse antidepressant response. The inflammation may damage the blood-brain barrier, allowing immune cells to enter the brain and cause ongoing neuronal injury that standard antidepressants aren’t designed to address.
For this subgroup, some research suggests that treatments with anti-inflammatory properties, such as ketamine, may work better than traditional antidepressants. If you developed depression for the first time after a COVID infection, or your previously well-managed depression became significantly harder to treat, the inflammatory aftermath of the virus is a likely contributor.
Fluvoxamine: An Antidepressant That May Help With COVID
One interesting twist in the COVID-antidepressant relationship goes the other direction. Fluvoxamine, an SSRI typically prescribed for OCD, was studied as a potential COVID treatment early in the pandemic. A meta-analysis of randomized controlled trials found that high-dose fluvoxamine reduced the risk of clinical deterioration by about 27% and lowered hospitalization rates by roughly 24% compared to placebo. Low doses didn’t show the same benefit.
The protective effect likely comes from fluvoxamine’s anti-inflammatory properties rather than its antidepressant action. If you happen to already take fluvoxamine, this is a minor silver lining, but it’s not a reason to start it solely for COVID protection. The finding does underscore the complex, bidirectional relationship between this virus and serotonin-system medications.
What This Means in Practice
If you take an antidepressant and get COVID, the most actionable risk involves drug interactions with Paxlovid. Before starting any COVID treatment, confirm with your prescriber that it’s compatible with your current medications. Trazodone and Paxlovid is a combination that needs dose adjustment or an alternative approach.
During the infection itself, be aware that your antidepressant may feel slightly different. Side effects could temporarily increase as inflammation slows drug metabolism, or effectiveness could dip as your serotonin levels drop. These changes are usually temporary. If your depression noticeably worsens in the weeks and months after COVID and doesn’t improve, that’s worth a conversation about whether the virus triggered an inflammatory pattern that requires a different treatment strategy.