Q. My doctor diagnosed depression and prescribed me the antidepressant sertraline. Over time, it caused a lack of emotion and a loss of libido.

She switched me to Wellbutrin. I experienced no side effects from this drug, and my sex life returned to normal. Then the insurance company switched me to the generic bupropion. It has caused horrible side effects.

I don’t want to go back to sertraline, but a loss of libido would be better than feeling so awful. Why can’t I get the brand name at an affordable price?

A. Many readers have complained about a lack of libido and other sexual side effects while taking antidepressants such as sertraline (Zoloft), escitalopram (Lexapro) or fluoxetine (Prozac). Bupropion (Wellbutrin), on the other hand, may actually help enhance sexuality. Some people report that Wellbutrin can increase libido. Other readers have reported that some generic bupropion formulations do not work as well as the brand name Wellbutrin.

Long-acting Wellbutrin (XL 300) could cost more than $3,000 a month in the U.S. In Canada, the same brand-name antidepressant could be under $200 for three months. You can learn a lot more about the pros and cons of various antidepressants in our “eGuide to Dealing with Depression.” It discusses sexual side effects in some detail. Our “eGuide to Saving Money on Medicines” also provides details on legitimate Canadian pharmacies. Both online resources may be found under the Health eGuides tab at www.PeoplesPharmacy.com.

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In their column, Joe and Teresa Graedon answer letters from readers. Write to them in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email them via their website: www.PeoplesPharmacy.com. Their newest book is “Top Screwups Doctors Make and How to Avoid Them.”