Call your doctor at once if you have a serious side effect such as: 1  headache with chest pain and severe dizziness, fast or pounding heartbeats, shortness of breath, fainting; 2  diarrhea that is watery or bloody;  fever, swollen glands, body aches, flu symptoms, new or worsening cough;
The maximum daily doses is also slightly different as both Wellbutrin XL and Wellbutrin have a maximum daily dose of 450 mg per day, whereas the maximum dosage for Wellbutrin SR is only 400 mg per day.
Summary: 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.