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How long does it take for Wellbutrin XL and SR to work?

Medically reviewed by Sally Chao, MD. Last updated on April 16, 2021.

Official answer


Wellbutrin is the brand name for the antidepressant drug bupropion. Like other antidepressants, it may take several weeks to notice the full effect of the medication, but it's typical to notice gradual improvement.

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

Your sleep, energy and appetite may start to improve in the first week or two. This can be an important sign that the drug is working. It often takes 6-8 weeks before you notice an improvement in your mood or regain interest in activities you enjoy.

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.

The difference in 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 March 2, 2021].
  2. Food and Drug Administration (FDA). Wellbutrin SR. August 2017. Available at:
    [Accessed March 3, 2021].
  3. Food and Drug Administration (FDA). Wellbutrin XL. May 2017. Available at:
    [Accessed March 3, 2021].

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