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Difference Between Wellbutrin SR and Wellbutrin XL

Wellbutrin SR vs Wellbutrin XL

Feeling sad is natural for most people especially when there is good reason to be. Some things might not go the way we originally planned them. It’s natural to feel sad, but when sadness becomes extreme and getting back up on your feet seems to be a difficult thing, it could become a real problem. If sadness persists even after a week and is interfering with your ability to socialize or mingle with other people and have fun, then it’s likely that you are going through depression. Fortunately, depression is not the end of everything; it can be treated. Various treatment methods are available, and this includes psychotherapy, group discussions, and even the use of medications. Several antidepressants are now available and have been proven effective in making symptoms of depression disappear. One of the medications prescribed for depression is Buproprion, under the trade name Wellbutrin. Wellbutrin is available in XL and SR formulations, but what is the difference between the two?

Wellbutrin contains the active ingredient Bupropion. Bupropion is an antidepressant and, at the same time, a smoking cessation aid. It works by increasing the levels of certain chemicals in the brain which are responsible for pleasurable feelings. With a proper dosing regimen, the drug is effective in treating the condition. The risk of developing serious side effects is low, but if the drug is misused and abused, potentially life-threatening effects may occur.

Wellbutrin is the antidepressant formulation of Bupropion while Zyban is the formulation used to help people quit smoking. Bupropion is available in XL and SR formulations. Both formulations are called time-controlled release formulations. “XL” attached to the end of the drug name stands for “extended release” while “SR” means “sustained release.”
Wellbutrin SR means that the dose of Bupropion is slowly released into the body throughout the day with the goal of maintaining a constant drug concentration in the bloodstream. Wellbutrin XL releases the dose for an extended period of time in a day. The SR formulation is slowly released in 12 hours while the XL doses are released for a period of 24 hours.
The dosing recommendations for both Wellbutrin formulations also differ since both drug delivery systems are controlled by time. Wellbutrin SR is initially given as 150mg once daily, and after 4 days the dose can be increased to twice daily to achieve a constant drug concentration in the blood. On the other hand, the extended release form is usually given once a day since the dose is being released in a 24-hour time frame.

There are benefits to using time-release medications like Wellbutrin XL and SR. These include:

  • Uniform release of the drug dose in the body.
  • Minimized side effects.
  • And better patient compliance.

These benefits are common to both formulations, but more benefit is obtained through Wellbutrin XL.

The most obvious advantage of the extended release formulation is the reduced frequency of drug intake which will result in better patient compliance. Patients find it inconvenient to have to take the drug at certain periods of time, especially for such drugs like Wellbutrin where it needs to be taken for a certain period of time. There may always be instances where a patient will forget a dose and will simply skip it which can affect the overall effectiveness of the drug regimen.

In the case of Wellbutrin, the XL formulation is taken only once a day compared to Wellbutrin SR where it is taken twice daily. Of course, the more convenient formulation will be the one where the patient will have a reduced frequency of popping medications. In addition, you don’t need to take Wellbutrin XL as often so there would be fewer side effects. When using these kinds of medications, always consult your doctor.


  1. Wellbutrin XL is the extended release formulation while Wellbutrin SR is the sustained release form.
  2. Both drugs are time-controlled release formulations.
  3. The Wellbutrin SR dose is released in a 12-hour period while the Wellbutrin XL dose is released in a 24-hour period.
  4. Both drugs produce, more or less, the same side effects but to a lesser extent with Wellbutrin XL.
  5. The dose for Wellbutrin XL is once daily, while the Wellbutrin SR dose is usually taken twice a day.

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  1. I searched many responses to my question regarding prescription differences between Bupropion XL and SR and didn’t get a clear and thorough answer until I hit this website. This posting was very helpful. Thank you!

  2. I never remember this difference

  3. Thank you sooo much ! I just switched from bupropion sr to Xl and this article is answered all of my questions !

  4. Thank you your website explained it very well. There is no other website that explained it the way yours did. The l you again

  5. I agree with other respondents that this article explain the difference between the SR and XL very well. I’m also interested to know if the XL has caused sleep disturbances for anyone.

    • Hey Betsy. I have been taking the XL for a while now and I have not had any sleep problems related to this drug. In fact, it has helped me lose weight which I needed. It took a little while to get in my system good and to start working but the last 3 months I have lost 33 lbs. Hope this has helped you.

      • Wow Lori! That is great news. I’m on the XL now and it is working well for me for sustained energy throughout the day. I need to lose weight from being on Depakote so I’m thrilled that you’ve had such great success in that area. I’m off Depakote and look forward to weight loss. Thank you so much.

    • My current doctor switched me from Prozac, which I was taking for over 5 yrs., and was causing me to feel so bla and useless and tired, to Bupropion 300XL once a day. It has been a miracle for me! Not only do I feel great and like my old good self, but my joint pain has mostly disappeared….and I am 70 yrs old!
      To answer your question about sleep, it has not disturbed my sleep at all and in fact sleep seems to have improved, plus I wake up on my own and feel good!!! As I said, it was a miracle for me.
      Good luck!!

    • Yes, I have definitely had trouble with sleeping since I recently started taking welbutrin 150XL
      I was relieved reading your post…to hear my problem was not just myself! I am actually going to speak with my Dr. about switching to welbutrin 12hr.SR instead of the wellbutrin 24hr. XL.
      I’m hoping that the
      12hr. SR
      will naturally have less interference with my sleep than this 24hr. XL. I hope this post was a bit helpful.

    • TheXL was partly to blame for my shakiness and agitation
      I just switched from XL to SR and seems to work better for me
      Remember though that we’re all different

    • Hello Betsy, I have had sleep disturbances with 150 mg of the XL. Vivid dreams and nightmares every night. And I have way too much energy in the evening, laziness during the day.My doctor has switched me to the SR 100mg 2x per day to see if that will make a difference. She said I may be metabolizing the XL too slowly. I was also taking 100 mg of seroquel and have been raised to 150 now to try and combat the sleep issues that wellbutrin has caused. She said she has never heard of anyone having this problem but sees how it is possible. My medication was adjusted today, the date that I am responding to your post.

  6. I’m wondering if anyone has had success taking the XL and SR together in the morning. The XL has worked well for me for the past couple of years but I’m finding that I have plateaued and need an extra boost. Is it possible to take a smaller dose of the SR in addition to the XL?

    • I was on the 300 XL in the morning and 150 SR in the afternoon/evening. So it’s possible.
      My dr switched me to 2 SR 150 in the morning and 1 150 SR in the afternoon but I don’t really like it. I find it wears off too quick for me.

  7. Hello,
    Does anyone have any advice? I have been taking Fluoxetine (generic of Prozac) for three years with terrible side effects (muscle and joint pain, fatigue, low energy, feeling cold, weight gain). My doctor suggested Wellbutrin and I took my first 150mg XL dose. I felt great. I immediately had energy to exercise (didn’t on Fluoxetine, had increased appetite so put on 22 lbs). On Wellbutrin, I did not feel hungry at all. However, when it came to sleeping, I couldn’t (I am a long-term insomniac). So I bit the pill in half the next morning, and took half before going to work. Only when I read the package insert this evening, did I see you are not supposed to split them. I am thinking of going on to 75 mg Sustained Release (SR), because at least that wears off after 12 hours, or taking a 50mg immediate release one twice a day. Has anyone any suggestions? I loved this medication – feel great on it except for the sleeping part.

  8. Why the doctor presribe for some patients sr and for others er ?

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