If you’ve been prescribed or are considering the medication bupropion, you might have noticed there are two versions: bupropion SR (sustained release) and bupropion XL (extended release). While they contain the same active ingredient and treat some of the same conditions, there are key differences to consider.

Whether you're using bupropion for depression, ADHD, seasonal affective disorder or smoking cessation, choosing the right formulation can make a big difference in how effective the medication is for you. In this guide, we’ll compare bupropion SR and XL, side effects to watch for, cost comparisons and how to decide which option fits best with your lifestyle and treatment goals.

• Bupropion SR releases medicine quickly and is taken twice daily. Bupropion XL releases slowly and is taken once daily.

• SR is FDA-approved for major depression and smoking-cessation. XL treats depression, seasonal affective disorder (SAD), and adult ADHD.

• Side-effect profiles of SR and XL are similar, so the choice usually comes down to treatment goal, dosing convenience, and your provider’s advice.

What is bupropion (Wellbutrin^®)?

Bupropion is a medication prescribed to treat depression, seasonal depression and adult ADHD. It belongs to a class of medications called nontricyclic antidepressants. It works by increasing the neurotransmitters dopamine and norepinephrine.¹ Bupropion is also used as a smoking cessation tool.²

In a meta-analysis of bupropion studies, 4 out of 5 studies showed a statistically significant decrease in depression symptoms versus a placebo. Bupropion also performed equally with other popular antidepressants like SSRIs.³

In a study focused on adult ADHD, 53% of participants reported at least a 30% reduction in symptoms after eight weeks of bupropion use. While not as effective as stimulants, bupropion is much better tolerated with minimal adverse effects reported.⁴

When it comes to smoking cessation, approximately 1 in 5 people successfully quit and remain nonsmoking after one year of bupropion use.⁵

Bupropion is available in two formulas, sustained release (SR) and extended release (XL).

Bupropion SR (Sustained Release) Overview

Bupropion SR is FDA approved for the treatment of major depressive disorder and smoking cessation. It is available in 100 mg and 150 mg doses. Dosing schedule will vary among individuals, so always follow your provider’s instructions.

Bupropion SR is released quickly into the bloodstream and is usually taken twice a day. A common dosing schedule would be two 150 mg tablets per day — one in the morning and one in the evening, at least eight hours apart. Your provider may start you out at once a day to reduce adverse side effects.⁶

Peak concentration of bupropion SR occurs approximately three hours after ingestion and can remain active for up to two days. Users typically start to see therapeutic results in the second week of bupropion SR use.⁷

A RedBox Rx prescription for bupropion starts at $25 per month, with purchase of a three-month supply. The telehealth consult with a licensed professional is $35.

Bupropion XL (Extended Release) Overview

Bupropion XL is prescribed to treat depression, seasonal depression⁸ and ADHD.⁹ The medication primarily comes in 150 mg and 300 mg doses. Recommended starting dose is 150 mg, once a day. Your provider will likely start you on a lower dose and increase as needed.¹⁰

Bupropion XL is designed to last longer and hits peak concentrations at around five hours after ingestion. It can remain active for up to two days. Results usually take at least two weeks to emerge.¹¹

Prescriptions start at $25 per month, with purchase of a three-month supply. An online consult with a licensed professional is $35.

Bupropion Side Effects & Risks

Because they share an active ingredient, bupropion SR and bupropion XL have similar side effects and risks. There is some research to suggest that bupropion XL is less likely to cause insomnia than bupropion SR, although both have side effects that could disturb sleep.¹²

Shared side effects of bupropion SR and bupropion XL include:¹³

• Drowsiness

• Anxiety

• Excitement

• Difficulty falling asleep or staying asleep

• Dry mouth

• Dizziness

• Headache

• Nausea

• Vomiting

• Stomach pain

• Uncontrollable shaking of a part of the body

• Loss of appetite

• Weight loss

• Constipation

• Excessive sweating

• Ringing in the ears

• Changes in your sense of taste

• Frequent urination

• Sore throat

Both bupropion SR and bupropion XL carry a risk of suicidal thoughts. If you are experiencing any thoughts of self-harm, please seek emergency help or dial 988 to reach the Suicide and Crisis Lifeline.

Bupropion SR vs. XL Comparison Chart

How to Choose: Bupropion SR vs. XL

Deciding between bupropion SR and XL comes down to your treatment goals, lifestyle and how your body responds to medication. While both versions contain the same active ingredient and are similarly priced, there are key differences that might make one a better fit for you.

Factors to Consider

• Treatment Goals. If you’re using bupropion for smoking cessation, the SR formulation is typically recommended. For seasonal depression (SAD) or ADHD, bupropion XL is more commonly prescribed. Both can be effective for treating major depressive disorder, so your provider may choose based on other factors.

• Daily Routine and Medication Adherence. Bupropion SR requires twice-daily dosing, which may be less convenient if you have a busy or unpredictable schedule. Bupropion XL is once daily, often making it easier to stick to. If you tend to forget midday doses, the XL version may be the better option.

• Side Effect Tolerance. Both versions have similar side effect profiles, but bupropion XL may be less likely to cause insomnia. If you’re sensitive to sleep disturbances, this might be an important consideration.

• Clinical Advice. This will be the deciding factor in your prescription. Your healthcare provider will weigh these factors alongside your personal health history and medication preferences. If one formulation doesn’t work well for you, switching to the other could be an option.

How RedBox Rx can help

RedBox Rx makes receiving bupropion XL, bupropion SR and other mental health treatments easy and affordable. We offer secure, private online consultations with licensed providers focused on your health.

Benefits of RedBox Rx include:

• Transparent, affordable, flat rates.

• Medications for $25 per month (with purchase of three-month supply).

• Low-cost consultations with a U.S. licensed medical professional.

• No insurance required. No membership fees. HSA and FSA eligible.

• No office wait times or scheduling issues typical with physical medical practices.

• FREE shipping directly to you. Monthly and quarterly subscriptions available.

Get started on your treatment journey with an online assessment for depression, seasonal depression or adult ADHD.

If you are experiencing suicidal or self-harm thoughts, please reach out immediately to a health care provider or call the National Suicide Prevention Lifeline at 1-800-273-8255.