There is no single “worst” antidepressant, because these medications can be problematic in very different ways. One drug might work well but cause brutal withdrawal symptoms. Another might be easy to stop but dangerous in overdose. The antidepressants that consistently rank worst across multiple dimensions are paroxetine (Paxil), venlafaxine (Effexor), amitriptyline and other older tricyclics, and the MAOIs. Which one matters most depends on what “worst” means to you.
Worst for Withdrawal Symptoms
Paroxetine and venlafaxine are the two antidepressants most notorious for withdrawal problems. When patients stop paroxetine abruptly, studies find that 42% to 66% experience discontinuation symptoms: dizziness, electric shock sensations in the head (often called “brain zaps”), nausea, irritability, and flu-like feelings. In one study that interrupted treatment for just five days, paroxetine triggered 13 out of 17 possible withdrawal symptoms on a standardized scale. Sertraline caused 3 out of 17. Fluoxetine (Prozac) caused none.
Venlafaxine produces what researchers describe as “the most serious discontinuation reactions” among common antidepressants. Its short half-life means the drug leaves your system quickly, and your brain notices. Fluoxetine, by contrast, lingers in the body for days after the last dose, giving your brain time to adjust. That’s why fluoxetine consistently shows the lowest withdrawal rates, sometimes approaching zero in clinical trials.
If you’re concerned about eventually stopping medication, the half-life of the drug matters enormously. Paroxetine and venlafaxine clear the body fast, which is exactly what makes stopping them so difficult. Escitalopram has also been shown to produce significantly fewer withdrawal symptoms than either of those two.
Worst for Sexual Side Effects
Sexual dysfunction is one of the most common reasons people want to switch or quit antidepressants, and SSRIs and SNRIs are the main culprits. The rates are strikingly high: in one large study, citalopram caused sexual problems in 73% of patients, paroxetine in 71%, venlafaxine in 67%, and sertraline in 63%. Problems include reduced desire, difficulty with arousal, and inability to reach orgasm.
Paroxetine again stands out as one of the worst offenders. In a study of over 6,000 outpatients, 65% of those on paroxetine reported sexual side effects. A head-to-head comparison found that 61% of men taking sertraline developed orgasm problems during a 16-week trial, compared with just 10% of men taking bupropion. Among women, the gap was similarly large: 41% versus 7%.
Bupropion (Wellbutrin) is the clear outlier here. Only about 14% to 25% of patients report sexual problems with bupropion, roughly a third the rate seen with SSRIs. This is because bupropion works through different brain chemistry, affecting dopamine and norepinephrine rather than serotonin. Mirtazapine also tends to cause fewer sexual side effects than SSRIs, though its rates (around 36%) are still higher than bupropion’s.
Worst for Weight Gain
Mirtazapine (Remeron) and the older tricyclics like amitriptyline cause the most weight gain. Mirtazapine adds an average of about 1.7 kg (nearly 4 pounds) in the first 12 weeks alone, and the gain often continues beyond that. Amitriptyline is similar, with studies showing 1.5 to 2 kg of gain in the same timeframe. Nortriptyline, another tricyclic, averaged 2 kg.
Among SSRIs, paroxetine is the worst for weight, with gains ranging from about 0.4 kg to 2.7 kg and a 21% higher risk of gaining 5% or more of body weight. The mechanism is largely the same across these drugs: they block histamine receptors in the brain, which increases appetite. Paroxetine also has strong effects on another receptor system that stimulates hunger.
SSRIs like sertraline and fluoxetine tend to be closer to weight-neutral, and bupropion sometimes causes modest weight loss.
Most Dangerous in Overdose
Older tricyclic antidepressants are far more lethal in overdose than newer medications. A large study of deaths in England and Wales found that tricyclics as a class were roughly 28 times more toxic than SSRIs when accounting for how often each was prescribed. Within the tricyclic group, dosulepin (also called dothiepin) was the deadliest, with a toxicity index 3.2 times higher than amitriptyline. Doxepin was 2.5 times more toxic than amitriptyline.
Among newer drugs, venlafaxine stands out. Its toxicity in overdose is about half that of amitriptyline but still roughly five times higher than SSRIs as a group. Mirtazapine falls in a similar range, slightly below venlafaxine. Within the SSRI class, citalopram is the riskiest in overdose, with a toxicity index about three times higher than other SSRIs. This is because citalopram can disrupt heart rhythm at high doses.
SSRIs overall are the safest class in overdose, which is one reason they became the default first-line treatment for depression.
Hardest to Tolerate Day to Day
A landmark analysis published in The Lancet compared 21 antidepressants across 522 trials and ranked them by “acceptability,” measured by how many patients dropped out for any reason. Clomipramine, an older tricyclic, was the only antidepressant where patients dropped out at a higher rate than people taking a placebo. Fluoxetine and agomelatine were the only two where patients were actually less likely to quit than the placebo group.
Tricyclics in general cause the most day-to-day side effects. Their anticholinergic properties (blocking a chemical messenger called acetylcholine) cause dry mouth, constipation, blurred vision, urinary retention, and drowsiness. Amitriptyline, nortriptyline, imipramine, and paroxetine score highest on anticholinergic burden scales. For older adults, this is especially concerning because high anticholinergic burden is linked to increased falls, memory problems, and faster cognitive decline.
Most Restrictive to Live With
MAOIs (monoamine oxidase inhibitors) like phenelzine and isocarboxazid require strict dietary restrictions that no other antidepressant demands. These drugs prevent your body from breaking down tyramine, an amino acid found in many common foods. Eating high-tyramine foods while on an MAOI can cause a sudden, dangerous spike in blood pressure that may require emergency treatment.
The restricted list is long: aged cheeses (cheddar, Parmesan, blue cheese, brie, feta), cured meats (pepperoni, salami, summer sausage), smoked or processed meats (bacon, bologna, smoked fish), fermented foods (sauerkraut, kimchi, pickles, tofu, kombucha, kefir), and even some caffeinated beverages. MAOIs also interact dangerously with many common medications, including other antidepressants, certain pain relievers, and decongestants.
MAOIs can be highly effective for treatment-resistant depression, but the lifestyle burden is real and makes them impractical for many people. They are rarely prescribed today for this reason.
Least Effective at Treating Depression
All approved antidepressants perform better than placebo, but the gap varies. The same Lancet meta-analysis found that reboxetine was the least effective antidepressant studied, barely edging out placebo. Fluoxetine, fluvoxamine, and trazodone also ranked toward the bottom for efficacy in direct comparisons with other antidepressants.
The most effective drugs in head-to-head trials were amitriptyline, escitalopram, mirtazapine, paroxetine, and venlafaxine. This creates a frustrating pattern: several of the most effective antidepressants are also the ones with the worst side effect profiles. Amitriptyline is potent but dangerous in overdose and loaded with anticholinergic effects. Paroxetine works well but causes significant weight gain, sexual dysfunction, and severe withdrawal. Venlafaxine is effective but hard to stop and riskier in overdose than SSRIs.
Which Antidepressants Come Up Worst Overall
Paroxetine appears on nearly every “worst” list: worst SSRI for withdrawal, worst SSRI for weight gain, worst for sexual side effects, and high anticholinergic burden. It is effective, but its side effect profile is consistently among the most burdensome of the SSRIs.
Tricyclics like amitriptyline and dosulepin combine high overdose risk, significant anticholinergic effects, weight gain, and sedation. Venlafaxine causes severe withdrawal, carries higher overdose risk than SSRIs, and triggers sexual dysfunction at rates comparable to the worst SSRIs. MAOIs impose dietary restrictions that most other antidepressants don’t require.
The “best” antidepressant for any individual depends on their specific vulnerabilities. Someone with a history of weight struggles faces different risks than someone concerned about sexual function or someone who has had trouble stopping medications before. What the research makes clear is that these trade-offs are real, measurable, and worth discussing before starting treatment.