The lowest manufactured dose of Wellbutrin is a 75 mg immediate-release tablet. For the extended-release version (Wellbutrin XL), the smallest available tablet is 150 mg, and the sustained-release version (Wellbutrin SR) also starts at 150 mg. Which one you’re prescribed depends on the formulation and the condition being treated.
Available Doses by Formulation
Wellbutrin comes in three formulations, each with different tablet strengths and dosing schedules:
- Immediate-release (Wellbutrin): Available in 75 mg and 100 mg tablets, taken two to three times per day. The 75 mg tablet is the absolute lowest dose of bupropion on the market.
- Sustained-release (Wellbutrin SR): Available starting at 150 mg tablets, typically taken once or twice daily.
- Extended-release (Wellbutrin XL): Available starting at 150 mg tablets, taken once daily in the morning.
There is also a brand called Aplenzin, which uses a slightly different salt form of bupropion. Its lowest tablet is 174 mg, which delivers roughly the same amount of active drug as 150 mg of standard bupropion.
Standard Starting Doses
For major depressive disorder, the recommended starting dose of Wellbutrin XL is 150 mg once daily. After four days, prescribers typically increase it to the target dose of 300 mg once daily. The original immediate-release version starts at 200 mg per day total, split into two 100 mg doses, with a possible increase to 300 mg per day (100 mg three times daily) after three days.
For seasonal affective disorder, the starting dose is also 150 mg once daily of the XL formulation. The increase to 300 mg happens after seven days rather than four. For smoking cessation, the sustained-release form (marketed as Zyban) begins at 150 mg once daily for the first three days before moving to 150 mg twice daily.
So while 75 mg tablets exist, most people start treatment at 150 mg or higher. The 75 mg dose plays a more specific role.
When a 75 mg Dose Is Used
The 75 mg tablet is primarily used for people with liver problems. The FDA label is specific here: for patients with moderate to severe liver impairment, the maximum dose of Wellbutrin is 75 mg per day. For mild liver impairment, the guidance is to reduce the dose or take it less frequently rather than capping it at a specific number.
People with kidney impairment may also need a lower dose or less frequent dosing, though the label doesn’t specify a fixed number the way it does for liver disease.
Some prescribers also use the 75 mg tablet when tapering a patient off bupropion gradually, or as a brief starting dose for someone who tends to be sensitive to medications, though these aren’t formally outlined in the prescribing information.
Why You Shouldn’t Cut Pills to Get a Lower Dose
If you’re on Wellbutrin SR or XL and want a lower dose, cutting the tablet is not a safe shortcut. Both formulations use a special coating that releases the medication slowly over hours. Crushing or splitting them dumps the full dose into your system at once, which raises the risk of side effects, including seizures.
The manufacturer states that SR and XL tablets should be swallowed whole and not cut, chewed, or crushed. Some sources have noted that SR tablets can technically be split in half once, just before taking them, but this contradicts the manufacturer’s recommendation. XL tablets should never be split under any circumstances.
If you need a dose lower than 150 mg, the immediate-release formulation is the appropriate option because it comes in that 75 mg tablet. Switching formulations requires a prescription change, so it’s not something to do on your own.
Seizure Risk and Dose
One reason dose matters with Wellbutrin is that seizure risk increases as the dose goes up. At 300 mg per day of the sustained-release form, the estimated seizure rate is about 0.1%. At 450 mg per day, it rises to roughly 0.35% to 0.44%. This is one reason bupropion has a hard ceiling of 450 mg per day and why prescribers start low before increasing. At 75 mg or 150 mg, the risk is lower still, which is part of why a gradual ramp-up is standard practice.
The Bottom Line on Dose Range
Wellbutrin’s full therapeutic range spans from 75 mg to 450 mg per day, depending on the formulation and the person’s medical situation. Most people taking it for depression will land between 150 mg and 300 mg daily. The 75 mg immediate-release tablet is the lowest manufactured dose and is used mainly for people whose bodies can’t clear the drug as efficiently, particularly those with liver disease. If your current dose feels too high, the path to a lower one runs through your prescriber, not a pill splitter.