What's the difference between Wellbutrin XL and SR?
Medically reviewed by Sally Chao, MD. Last updated on April 16, 2021.
Wellbutrin XL and SR are different formulations of the same drug. One is not better than the other. The differences between Wellbutrin XL and Wellbutrin SR are found in the dosing and the approved uses. XL stands for extended release; it only needs to be taken once per day. SR stands for sustained release; it may be taken twice per day.
The generic name for the drug is bupropion. Bupropion is an antidepressant medication that works by changing the levels of chemicals in the brain.
There is no difference in strength between Wellbutrin XL and SR. The difference lies in how you take your dose. Once these drugs are stable in your system, they are designed to work at the same strength. You should not change between Wellbutrin XL and SR on your own. Your doctor may switch formulations depending on your diagnosis and response to treatment.
Wellbutrin XL is approved to treat major depressive disorder and seasonal affective disorder (SAD). SAD is depression that occurs mainly in the fall and winter.
The dose for Wellbutrin XL starts at 150 mg once per day, and may go up to 300 mg once per day. The dose is the same for both major depressive disorder and SAD. The daily dose is usually taken in the morning.
Wellbutrin SR is only approved to treat major depressive disorder. The dose starts at 150 mg once per day and may increase to 150 mg twice per day. Wellbutrin SR is usually taken in the morning and midafternoon.
If you miss a dose of Wellbutrin SR, you should take it as soon as you remember and then continue with your usual dose schedule. However, because Wellbutrin XL is an extended-release medication, if you miss a dose, do not take it when you remember. Take it the next day at the usual time.
Do not stop taking Wellbutrin SR or XL on your own. Talk to your health care provider first.
- National Alliance on Mental Illness (NAMI). Bupropion (Wellbutrin). December 2020. Available at: https://www.nami.org/About-Mental-Illness/Treatments/Mental-Health-Medications/Types-of-Medication/Bupropion-(Wellbutrin). [Accessed March 2, 2021].
- Food and Drug Administration (FDA). Wellbutrin XL Prescribing Information. May 2017. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/021515s036lbl.pdf. [Accessed March 2, 2021].
- Food and Drug Administration (FDA). Wellbutrin SR Prescribing Information. October 2020. Available at: https://gskpro.com/content/dam/global/hcpportal/en_US/Prescribing_Information/Wellbutrin_SR/pdf/WELLBUTRIN-SR-PI-MG.PDF. [Accessed March 2, 2021].
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