The most common dose of Wellbutrin is 300 mg once daily, taken as an extended-release (XL) tablet in the morning. Most people start at 150 mg per day and increase to 300 mg after about four days. The absolute maximum is 450 mg per day, regardless of which formulation you take. How you get to your target dose, and how many pills you take each day, depends on which version of the medication you’re prescribed.
Three Formulations, Three Dosing Schedules
Wellbutrin comes in three forms, and each one releases the medication into your body at a different speed. That difference changes how many times a day you take it and how high each individual dose can be.
Extended-release (XL) is the most commonly prescribed version. You take it once a day in the morning, starting at 150 mg. After four days, the dose typically goes up to 300 mg once daily. The maximum is 450 mg once daily.
Sustained-release (SR) is taken twice a day, at least eight hours apart. You start at 150 mg once in the morning, then after three days move to 150 mg twice daily. The maximum is 200 mg twice daily, and no single dose should exceed 200 mg.
Immediate-release (IR) requires the most frequent dosing. The starting dose is 100 mg twice daily, increasing after three days to 100 mg three times daily. The maximum is 450 mg per day split across three or four doses, with no single dose above 150 mg.
The XL version became popular precisely because it simplifies things. One pill in the morning, no need to space multiple doses throughout the day.
Why the Starting Dose Is Lower Than the Target
Wellbutrin’s starting dose of 150 mg is intentionally lower than the 300 mg target most people end up on. This short ramp-up period, usually just three to four days, gives your body time to adjust and helps reduce side effects like headache, dry mouth, or trouble sleeping. Jumping straight to a higher dose increases the chance of those effects hitting harder than they need to.
Some people respond well at 150 mg and stay there. Others need 300 mg to feel a meaningful difference. If 300 mg isn’t enough after several weeks, a prescriber may raise the dose to 450 mg, but that’s less common and comes with additional risk.
The 450 mg Ceiling and Seizure Risk
The hard upper limit for Wellbutrin is 450 mg per day, and that limit exists because of seizure risk. The connection between dose and seizures is well documented: the estimated seizure incidence increases almost tenfold between 450 mg and 600 mg per day. That’s not a gradual climb. It’s a sharp jump that makes exceeding 450 mg genuinely dangerous.
Seizure risk also depends on how much medication hits your system at once, which is why each formulation has its own cap on single-dose size. With the IR version, no single dose should exceed 150 mg. With the SR version, the cap is 200 mg per dose. Spacing doses at least eight hours apart further reduces the risk by preventing drug levels from stacking up too high.
Doses for Smoking Cessation
When bupropion is prescribed to help quit smoking (sold under the brand name Zyban), the dosing schedule is slightly different. You start with 150 mg once daily for three days, then increase to 150 mg twice daily for the rest of treatment. The target is the same 300 mg per day, but you begin taking the medication one to two weeks before your planned quit date so it has time to build up in your system.
Doses for Seasonal Depression
For seasonal affective disorder, the XL formulation follows the same 150-to-300 mg range, but the timing of treatment is tied to the calendar. Treatment typically starts in early fall (September through November) at 150 mg daily, then increases to 300 mg for those who tolerate it. In the first week of spring, the dose tapers back down to 150 mg before stopping entirely. This seasonal on-off pattern is unique to this use of the medication.
What to Do if You Miss a Dose
If you miss a dose, skip it and take your next one at the regular time. Do not double up. With the SR and IR versions, maintaining at least eight hours between doses matters more than making up for a missed one. Taking two doses too close together raises your peak blood levels unnecessarily, which is exactly what the dosing rules are designed to prevent.
When the Dose Might Be Lower Than Usual
Certain health conditions can slow down how quickly your body clears bupropion, which means the standard dose could build up to higher-than-intended levels. People with liver disease, kidney problems, or a history of seizures often need a reduced dose or less frequent dosing. Older adults may also require adjustments, since the body’s ability to metabolize medications tends to slow with age. In these situations, staying at 150 mg rather than moving to 300 mg is a common approach.