Wellbutrin vs. Zoloft: How They Work Differently and Who Each May Suit

Searching “wellbutrin vs zoloft” usually means you’re weighing two quite different medications. Lexapro and Zoloft are close cousins, but Wellbutrin and Zoloft work in different ways and carry different warnings. Research doesn’t show that either one works better for depression overall.

What differs is the side effects and the cautions, and that’s what this post sets side by side, along with who each one tends to suit. It isn’t a recommendation for either; it’s a way to understand the trade-offs before you talk with your provider. The choice is one to make with your provider.

Two Different Ways of Working

Zoloft (sertraline) is an SSRI, a selective serotonin reuptake inhibitor. Its FDA label says it increases serotonin activity in the brain by blocking serotonin’s reuptake into nerve cells. Serotonin is one of the brain’s chemical messengers.

Wellbutrin (bupropion) belongs to a different group. Its FDA label says it weakly blocks the reuptake of two other messengers, norepinephrine and dopamine, and doesn’t block the reuptake of serotonin. The label is also candid that how bupropion relieves depression is unknown, as it is for other antidepressants.

Both are sold under their brand names and as generics. Bupropion comes in regular, sustained-release and extended-release tablets, and this post draws on the Wellbutrin XL (extended-release) label. The same active ingredient is also sold as Zyban to help people quit smoking, an approval Wellbutrin XL itself doesn’t carry. Because the two medications work differently, their side effects and cautions differ more than those of two SSRIs.

What Each Is FDA-Approved to Treat

The labels list different approved uses. For adults:

• Zoloft (sertraline): major depressive disorder, OCD, panic disorder, PTSD, social anxiety disorder and premenstrual dysphoric disorder (PMDD).
• Wellbutrin XL (bupropion): major depressive disorder, and preventing depressive episodes in people with seasonal affective disorder, depression that returns each fall and winter.

Zoloft’s list is longer and includes several anxiety-related conditions, while Wellbutrin XL is the one with a specific approval for preventing winter depression. Both labels say to screen for bipolar disorder before starting, because an antidepressant can set off mania or hypomania, and Wellbutrin XL’s label adds that it isn’t approved for bipolar depression.

What’s on a label reflects what was studied for approval, which isn’t the whole story of what a medication can do. Providers may prescribe an approved medication for another use when they judge it medically appropriate. This is called off-label use.

What Research Shows About How Well They Work

For depression overall, the two look about equally effective. A U.S. pooled analysis of 7 randomized trials comparing bupropion with SSRIs, including sertraline, found nearly identical response rates (62% and 63%) and remission rates (47% for both) at 8 weeks, with both better than placebo. A 16-week U.S. trial comparing bupropion and sertraline directly found no difference on any of its depression or anxiety rating scales. A broader review funded by the U.S. Agency for Healthcare Research and Quality, covering 234 studies of newer antidepressants, found no clinically relevant differences in how well they worked for depression. In the largest analysis, Cipriani and colleagues in 2018, an international study, sertraline was among the better-tolerated antidepressants, while the certainty of the evidence was low to very low for most comparisons involving bupropion. A 2023 American College of Physicians guideline recommends a second-generation antidepressant, a group that includes both, and says the choice should be personalized around side effects, symptoms, other conditions, other medicines and preferences.

The two have also been compared as a second step. In the STAR*D study, a large U.S. study funded by NIMH, 727 adults whose depression hadn’t gone away on the SSRI citalopram, or who couldn’t tolerate it, were randomly assigned to switch to bupropion, sertraline or venlafaxine. About 1 in 5 to 1 in 4 reached remission, depending on the rating scale, and the three medications didn’t differ significantly in outcomes or side effects.

Averages like these can’t predict how one person will respond. Where the two really differ is in side effects and cautions.

Sexual Side Effects

This is where the research is most consistent. Zoloft’s label warns that SSRIs may cause delayed or failed ejaculation, lower desire and erectile dysfunction in men, and lower desire and delayed or absent orgasm in women, and it tells prescribers to ask about sexual function before and during treatment. In Zoloft’s trials, ejaculation failure (8% of men, versus 1% on placebo) and lower desire (6%, versus 2%) were among the most common side effects.

Bupropion has come out lower in several kinds of studies:

• A direct comparison. In a U.S. trial of 248 adults who were in a stable relationship and had normal sexual function at the start, 63% of men and 41% of women on sertraline developed sexual dysfunction over 16 weeks, compared with 15% and 7% on bupropion.
• Pooled trials. The pooled analysis of 7 trials found significantly more sexual side effects with SSRIs than with bupropion or placebo, and no more with bupropion than with placebo.
• A large U.S. survey. Among 6,297 primary care patients, rates were 22% to 25% with bupropion and 36% to 43% across SSRIs, mirtazapine and venlafaxine XR taken together. This was a one-time survey, so it shows how common the problems were, not what each medication caused.
• An international analysis. A pooled analysis of studies that asked about sexual function directly, from Italy, which mixed different study designs, including open-label studies, found bupropion’s rates didn’t differ significantly from placebo’s.

Lower isn’t zero. Wellbutrin XL’s label lists impotence and abnormal ejaculation among reports received after it went on the market. Sexual changes can also come from depression itself, as Zoloft’s label notes. Rarely, sexual side effects have been reported to last after an SSRI is stopped. We go further in sexual side effects of antidepressants.

Weight, Sleep and Energy

Weight. In a 2024 study of 183,118 U.S. patients, bupropion was the antidepressant consistently linked to the least weight gain. At 6 months, people who started it gained about half a pound less on average than people who started sertraline, and they were 15% less likely to gain 5% or more of their starting weight. That’s a small difference, the study was observational, and many patients stopped their medication along the way. In the 16-week direct trial, weight didn’t differ between the two. Wellbutrin XL’s label reports that in depression trials of the sustained-release form, more people lost 5 pounds or more on bupropion than on placebo, with a dose-related drop in weight, and that more people lost 5 pounds or more in its seasonal depression trials of the extended-release form.

Sleep and energy. The two tend to differ here too:

• Wellbutrin XL: trouble sleeping is one of its most common side effects, along with dry mouth, nausea, dizziness and feeling anxious. The label says to take it in the morning, and its Medication Guide says not to take it too close to bedtime if you have trouble sleeping.
• Zoloft: in its trials, both sleepiness (11%, versus 6% on placebo) and trouble sleeping (20%, versus 13%) were more common than with placebo. Nausea (26%, versus 12%) and diarrhea or loose stools (20%, versus 10%) were its most common side effects.
• Research comparing them: a U.S. pooled analysis of 6 trials found that sleepiness and fatigue from depression improved more with bupropion than with SSRIs, though the authors called the results preliminary. In the direct trial, sleepiness, nausea, diarrhea and sweating were more common with sertraline.

Which of these matters most depends on you. Someone already sleeping too much may weigh them differently from someone who lies awake at night.

Anxiety: Where the Labels Differ Most

If anxiety is part of the picture, the labels point in different directions. Zoloft is FDA-approved in adults for several anxiety-related conditions: panic disorder, social anxiety disorder, OCD and PTSD. Bupropion isn’t approved for any anxiety disorder, and its label lists anxiety and agitation among its most common side effects.

Anxiety that comes with depression is a different question, and there the research is mixed. A pooled analysis of 10 trials found that bupropion and SSRIs eased anxiety symptoms in depression about equally. Another analysis by the same U.S. research group looked at people whose depression came with high levels of anxiety and found a modest edge for SSRIs: response rates of 65% versus 59%. The authors calculated that about 17 people would need an SSRI instead of bupropion for 1 more person to respond.

Neither is FDA-approved for generalized anxiety disorder, so for that condition either would be off-label. So the honest summary is that Zoloft has the anxiety-related approvals, and the evidence for anxiety within depression is closer than many people assume. Our anxiety disorders guide explains how these conditions differ.

Cautions That Differ

Seizures are bupropion’s best-known caution. Its label says bupropion can cause seizures and that the risk is dose-related, which is why the dose is raised gradually and why the label says not to take an extra dose to make up for a missed one. The risk also depends on personal health factors and other medications. The label lists things that raise it, including diabetes treated with insulin or diabetes pills, misuse of stimulants or use of cocaine, heavy use of alcohol, sedatives or opioids, a serious head injury, a brain tumor or infection, a severe stroke, and metabolic problems such as low sodium or low blood sugar. Zoloft’s label, by contrast, advises caution in people with a seizure disorder rather than ruling it out.

Wellbutrin XL’s label says not to take it if you:

• Have a seizure disorder.
• Have or have had bulimia or anorexia nervosa, because seizures were more common in people with these eating disorders.
• Are abruptly stopping alcohol, benzodiazepines, barbiturates or seizure medicines.
• Have taken an MAOI (an older group of antidepressants) in the past 14 days, or are being treated with linezolid (an antibiotic) or intravenous methylene blue. An MAOI also shouldn’t be started within 14 days of stopping bupropion.
• Are allergic to bupropion or the tablet’s other ingredients.

Its Medication Guide adds that it shouldn’t be taken with any other medicine containing bupropion, such as Zyban. The label also says bupropion can raise blood pressure, sometimes to the point of high blood pressure, so blood pressure should be checked before starting and from time to time during treatment. It also warns about psychiatric reactions such as delusions, hallucinations or psychosis, and says bupropion can cause a false-positive result for amphetamines on some urine drug screens. Both labels warn about angle-closure glaucoma, a type of glaucoma, in people with narrow eye angles.

Zoloft has its own list. It can’t be taken with MAOIs, including linezolid and intravenous methylene blue, or within 14 days of stopping one, and an MAOI shouldn’t be started within 14 days of stopping Zoloft. It also can’t be taken with pimozide, and the liquid form contains alcohol, so it can’t be used with disulfiram. Its warnings include serotonin syndrome (a rare but serious reaction), a higher risk of bleeding, especially with aspirin, anti-inflammatory pain relievers or blood thinners, low sodium, and heart rhythm (QT) changes in people with risk factors. Wellbutrin XL’s Warnings and Precautions section doesn’t include those. Our post on Lexapro vs. Zoloft covers Zoloft’s warnings in more detail.

Alcohol and Both Medications

Zoloft’s Medication Guide, the handout written for patients, says not to drink alcohol while taking it. Wellbutrin XL’s label says alcohol should be minimized or avoided, describes rare reports of reduced alcohol tolerance, and lists excessive drinking as something that raises seizure risk. None of the labels we reviewed sets a safe amount.

Stopping drinking suddenly matters too. Bupropion must not be used while someone is abruptly stopping alcohol, and its Medication Guide tells people who drink a lot to talk with their provider before suddenly stopping. Ask your provider or pharmacist before drinking any amount. Our post on whether you can drink on antidepressants goes through the labels medication by medication.

Taking Them Together

Sometimes the question isn’t either-or. Adding bupropion to an SSRI is a common strategy when an SSRI alone hasn’t been enough, but no FDA label approves the combination, so it’s off-label use. In the STAR*D augmentation trial, adults whose depression hadn’t gone away on citalopram were randomly assigned to add bupropion or buspirone. Remission rates were similar, at about 30%, while bupropion brought a greater drop in symptoms and fewer people stopping because of side effects. There was no placebo group.

Adding bupropion has also been studied for SSRI sexual side effects. A Cochrane review, an international review based in the UK, found that it helped at the higher of the two amounts studied, but not the lower. This is off-label as well.

Combining them takes care. Wellbutrin XL’s label says bupropion blocks CYP2D6, one of the liver enzymes that clears sertraline, and names sertraline among the medications whose levels can rise, so doses may need lowering. The same label names antidepressants among medications that lower the seizure threshold and calls for extreme caution when combining them. Only your provider can weigh whether a combination makes sense for you.

How Long Each Takes to Work

About the same: a pooled analysis of 7 trials found no difference in how quickly people responded or reached remission. NIMH says antidepressants usually take 4 to 8 weeks to work, and that sleep, appetite, energy and concentration often improve before mood does. MedlinePlus says it may take 4 weeks or longer to feel the full benefit of bupropion and a few weeks or longer for sertraline.

Side effects often show up before the benefit does. Our post on feeling worse before you feel better walks through that stretch.

Stopping or Switching

Zoloft’s label describes symptoms that can follow stopping, especially stopping abruptly, and recommends lowering the dose gradually when possible. Wellbutrin XL’s label also says to taper the dose when stopping, in its general dosing instructions, not only at the end of the winter season. Switching from one to the other is something your provider plans with you, and our post on when to consider stopping medication explains how that conversation usually goes. Please don’t stop a medication on your own; some can cause withdrawal symptoms or a return of symptoms if stopped suddenly.

How the Choice Usually Gets Made

With no overall winner, the decision tends to rest on you rather than on a ranking:

• What’s being treated. Zoloft’s label covers OCD, panic disorder, PTSD, social anxiety disorder and PMDD; Wellbutrin XL’s covers preventing winter depression. Both cover major depressive disorder.
• Which side effects would bother you most. In studies, sexual side effects and weight gain have been less common with bupropion, while trouble sleeping and dry mouth are common with it. Stomach upset and sleepiness have been more common with sertraline. People vary.
• Seizures and eating disorders. Any history of seizures, a serious head injury, or bulimia or anorexia matters for bupropion.
• Blood pressure. Bupropion can raise it, so your provider will want a reading.
• Alcohol and other substances, including whether you drink heavily and plan to stop.
• Everything else you take, including over-the-counter medicines and supplements, because of the interactions above.
• Liver and kidney health. Wellbutrin XL’s label recommends a lower dose for people with moderate to severe liver problems, and considering a lower dose with mild liver problems or with kidney problems. Zoloft’s label recommends a lower dose for mild liver problems and doesn’t recommend it with more serious liver disease. Your provider will take that into account.
• Pregnancy or breastfeeding plans. Zoloft’s label describes possible breathing and adjustment problems in newborns after exposure late in pregnancy and a higher risk of bleeding after delivery. Wellbutrin XL’s label says studies of first-trimester exposure haven’t shown an overall increase in birth defects. Both note the risks of untreated depression, so plan with your provider. Our post on treating depression while breastfeeding has more.
• What you’ve taken before, and how it went.

If the first one doesn’t suit you, you’re far from alone, and why finding the right medication can take time explains what usually comes next. For adults in Mount Laurel and across New Jersey, this is the conversation our board-certified psychiatric nurse practitioners have with patients before a first prescription. Our depression guide covers the bigger picture of treatment. If you’re comparing SSRIs instead, see Prozac vs. Zoloft.

Frequently Asked Questions

Is Wellbutrin an SSRI?

No. Zoloft is an SSRI, but bupropion works on two other brain messengers, norepinephrine and dopamine, and its label says it doesn’t block the reuptake of serotonin. That’s a big part of why its side effects differ.

Is Wellbutrin or Zoloft better for anxiety?

Zoloft is FDA-approved for several anxiety-related conditions: panic disorder, social anxiety disorder, OCD and PTSD, and bupropion isn’t approved for any anxiety disorder. Neither is approved for generalized anxiety disorder. For anxiety that comes with depression, studies found the two eased anxiety symptoms about equally, with a modest edge for SSRIs when anxiety was high. Which fits depends on your symptoms and history.

Does Wellbutrin cause less weight gain than Zoloft?

In one large U.S. observational study, people starting bupropion gained about half a pound less at 6 months, on average, than people starting sertraline. In a 16-week head-to-head trial, weight didn’t differ. Individual results vary.

Which has fewer sexual side effects?

Bupropion has had lower rates than sertraline and other SSRIs fairly consistently across trials and surveys, though not zero. If sexual side effects are a concern, tell your provider before you start, so it’s part of the decision.

Can you take Wellbutrin and Zoloft together?

Sometimes, when your provider thinks it makes sense. Adding bupropion to an SSRI is a common off-label strategy, but it needs care: bupropion can raise levels of sertraline and other medications, and the bupropion label calls for extreme caution when combining it with medications that lower the seizure threshold, including antidepressants.

Can I switch from Zoloft to Wellbutrin?

People do switch. The STAR*D study switched people from citalopram, not from sertraline, so it doesn’t directly test a move from Zoloft to Wellbutrin. In that study, about 1 in 5 to 1 in 4 reached remission after switching, and sertraline, another SSRI, did about as well as bupropion, so not responding to one SSRI didn’t mean another would fail. Your provider can plan the change with you. Please don’t stop a medication on your own; some can cause withdrawal symptoms or a return of symptoms if stopped suddenly.

If you’d like help sorting out which approach fits, a psychiatric evaluation is a good place to begin, and medication management gives you regular follow-ups to adjust the plan as you go.

This article is for general educational purposes only. It does not constitute medical advice, does not establish a provider-patient relationship, and is not a substitute for individual evaluation, diagnosis, or treatment by a qualified clinician. If you’re in crisis or thinking about harming yourself, call or text 988 (Suicide & Crisis Lifeline), any time, day or night. In an emergency, call 911 or go to the nearest emergency room.