Wellbutrin SR vs XL Differences and Similarities to Know

If you’ve been prescribed Wellbutrin, you might be wondering about the difference between the SR (sustained-release) and XL (extended-release) versions. Both are used to treat depression, but they differ in how long they last and how often you take them. In this article, we’ll break down the key differences to help you better understand which option might be right for you.

What Is Wellbutrin?

Wellbutrin is a brand name for bupropion, an antidepressant in the norepinephrine-dopamine reuptake inhibitor (NDRI) class. Both Wellbutrin SR and Wellbutrin XL help improve mood and energy by increasing levels of two essential brain chemicals (neurotransmitters), norepinephrine and dopamine, in the brain. Unlike many other antidepressants, it doesn’t significantly affect serotonin.

What Are the Uses of Wellbutrin SR and XL?

Both Wellbutrin SR and Wellbutrin XL are norepinephrine and dopamine reuptake inhibitors (NDRIs) approved by the U.S. Food and Drug Administration (FDA) to treat major depressive disorder (MDD). Other uses of these medications are as follows: 

• Wellbutrin XL is FDA-approved to prevent seasonal affective disorder (SAD), a type of depression that typically occurs in the colder winter months. 

• Wellbutrin SR or bupropion SR (previously available as the brand name Zyban) is approved for smoking cessation. 

• A combination medicine (naltrexone-bupropion) is sold under the brand name Contrave and is used to help with weight loss.

• Off-label uses include treating attention deficit hyperactivity disorder (ADHD) and neuropathic pain. These uses are determined on a case-by-case basis using the provider’s clinical judgement.

Wellbutrin SR vs Wellbutrin XL: Key Differences

Wellbutrin SR releases the active ingredient over several hours, maintaining a steady concentration in the bloodstream, reducing the need for frequent dosing, improving effectiveness, and lowering the severity of side effects. Wellbutrin SR reaches maximum blood concentration in 3 hours and lasts 8-12 hours.

Wellbutrin XL also releases the active ingredient gradually but over a longer period than SR formulations. Typically, these work throughout a 24-hour period, thereby reducing dosing frequency to once daily and ensuring the drug’s effects are maintained for even longer. Wellbutrin XL reaches maximum blood concentration in 5 hours and lasts 12-24 hours.

The below chart further compares Wellbutrin SR vs. Wellbutrin XL to help you decide which one may be right for you:

How Long Does It Take to Work?

You may begin seeing improvements in mood and energy within 1-2 weeks of starting Wellbutrin, with full effects usually reached after 4-6 weeks. 

Some people report experiencing an increase in their energy levels early on, which can be helpful for fatigue-related depression.

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Which Is Better: SR or XL?

When it comes to choosing the right medication for your health, there are a lot of factors to consider. The following pros and cons can help you decide:

Wellbutrin SR 

• Pros:

  • Shorter half-life 

  • Less severe side effects

  • Can help with smoking cessation

• Cons:

  • Requires twice-daily dosing

  • Higher chance of missed doses

Wellbutrin XL

• Pros: 

  • Once-daily dosing

  • Prevent seasonal depression

  • Better symptom control

• Cons:

  • May be more stimulating

  • Not approved for smoking cessation

Side Effects of Wellbutrin XL vs. SR 

The side effects of both medications are similar, though the severity of symptoms can depend on the version you are taking.

Side effects are usually less severe with both Wellbutrin XL and Wellbutrin SR compared to the immediate release formulation. 

Common Side Effects

Common side effects include:

• Drowsiness

• Sleep problems 

• Anxiety, jitters

• Headache

• Dry mouth

• Nausea, vomiting, belly pain, constipation

• Loss of appetite

• Uncontrolled shaking

• Excessive sweating

• Changes in taste

• Tinnitus (ringing in the ears)

• Sore throat

• Frequent urination

Note: Mild withdrawal symptoms can develop if you stop taking Wellbutrin (bupropion) abruptly after long-term treatment or higher doses. Symptoms can include flu-like symptoms, fatigue, headaches, sleep disturbances, and mood changes.

Serious Side Effects 

Seek immediate medical attention for side effects such as: 

• Hallucinations

• Paranoia

• Muscle or joint pain 

• Rapid or irregular heartbeat

• Seizures

• Allergic reaction (skin rash, swelling of the face, lips, tongue, and throat, chest pain, and difficulty breathing)

Notably, studies have shown that bupropion (Wellbutrin SR and Wellbutrin XL) has a much lower risk of causing sexual dysfunction compared to other antidepressants like selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants.

Wellbutrin for Weight Loss  

Studies have shown that Wellbutrin XL may be slightly more effective than Wellbutrin SR for weight loss.

Note: Wellbutrin (bupropion) is not an FDA-approved weight loss treatment. Contrave is a brand name medication containing bupropion and naltrexone is approved by the FDA for this indication.

Wellbutrin and Sleep Concerns

Studies show that Wellbutrin can cause insomnia (difficulty falling asleep and staying asleep). However, dose timing can help reduce sleep issues while taking Wellbutrin.

Taking Wellbutrin XL in the morning can help minimize the risk of insomnia by ensuring lower drug levels in the evening. 

In contrast, taking a short-acting (IR) formulation later in the day significantly increases the chance of insomnia. 

If you are experiencing sleep problems, it is important to discuss this with your healthcare provider to determine if Wellbutrin XL may be a better treatment option for your mental health.

Drug Interactions and Precautions

It’s important to be aware of how Wellbutrin can interact with other drugs or supplements. Tell your doctor about any medications you’re taking, especially:

• Monoamine oxidase inhibitors (MAOIs)

• Antipsychotics

• Other antidepressants

• Stimulants or seizure medications

Avoid alcohol while on Wellbutrin, as it may increase the risk of seizures or other side effects.

FAQs

Who Should Not Take Wellbutrin?

Do not take Wellbutrin if you:

• Have a seizure disorder

• Have a current or past diagnosis of bulimia or anorexia

• Use or recently stopped using MAO inhibitors

• Are withdrawing from alcohol or benzodiazepines

Your doctor will weigh risks and benefits before prescribing.

Can You Switch Between Wellbutrin SR vs XL?  

Your healthcare provider may switch you from Wellbutrin SR to XL or vice versa based on your response and tolerability of side effects. 

Can You Take Wellbutrin With Other Antidepressants?

Your healthcare provider may prescribe Wellbutrin in combination with SSRIs like Zoloft or Lexapro to enhance the effects or to reduce side effects. This is called adjunct therapy and should only be done under close medical supervision.