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How long does it take Wellbutrin XL/SR (bupropion) to work?

Medically reviewed by Carmen Pope, BPharm. Last updated on Aug 22, 2022.

Official answer


You may notice an improvement in your sleep, energy and appetite in the first week or two of taking Wellbutrin and this can be an important sign that the drug is working. But, like other antidepressants, improvements in your mood or motivation may take 6 to 8 weeks to develop and it may be a few months before you regain an interest in the activities you used to enjoy. Bupropion is metabolized to three active metabolites once in the body, each with varying durations of action, and it's typical to notice a gradual improvement in your symptoms of depression over weeks to months.

Wellbutrin is the brand name for the antidepressant drug bupropion. Wellbutrin XL and SR both work the same way. Wellbutrin weakly blocks nerve cells in the brain (neurons) from taking up the brain neurotransmitters norepinephrine and dopamine after these chemicals have been released in the brain. Norepinephrine and dopamine are important for regulating mood and brain responses. Over time, taking Wellbutrin increases the amount of these neurotransmitters in the body, which may reduce symptoms of depression.

Not everyone has the same symptoms of depression, but common ones include:

  • Feeling sad, empty and hopeless (depressed mood)
  • Sleeping more or less than usual
  • Eating more or less than usual
  • No interest or pleasure in activities you usually enjoy
  • Trouble concentrating
  • Low energy
  • Nervous energy.

The difference between Wellbutrin XL and SR is the way the drug is released in your body. XL is "extended release" and only needs to be taken once a day. SR stands for "sustained release" and may be taken twice a day, usually in the morning and afternoon.

Wellbutrin XL comes in 150 mg and 300 mg tablets. Wellbutrin SR is also a tablet and comes in doses of 100 mg, 150 mg and 200 mg. You can take Wellbutrin with or without food.

Taking Wellbutrin can increase the risk of suicidal thoughts and behaviors, so close monitoring for these side effects is important. Some people may also be at risk for a seizure from taking Wellbutrin, so it's common to start on a low dose of the drug and increase it gradually over time for safety. This can also make it take longer for the drug to have its full effect.

Even if you do not notice improvement in your depression symptoms, you should not stop taking Wellbutrin. Also, do not take more than the prescribed dose because this can increase your risk of a seizure. It is also important not to take other mood-altering drugs, like alcohol and illegal drugs. These drugs can negatively affect the way Wellbutrin works.

  1. National Alliance on Mental Illness (NAMI). Bupropion (Wellbutrin). December 2020. Available at: [Accessed August 22, 2022].
  2. Food and Drug Administration (FDA). Wellbutrin SR. August 2017. Available at:
    [Accessed August 22, 2022].
  3. Food and Drug Administration (FDA). Wellbutrin XL. May 2017. Available at:
    [Accessed August 22, 2022].
  4. Wellbutrin Patient Tips. Updated May 26, 2022.

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