Hi, Champix (varenicline) medicine is used to help people quit smoking. While Champix can be an effective tool for smoking cessation, like all medications, it may cause side effects. Some of the known side effects of Champix include nausea, insomnia, abnormal dreams, headache, and changes in taste. Although rare, there have been reports of Champix causing changes in behavior, including aggression, agitation, and mood swings. In some cases, these changes have been severe and led to hospitalization. There have also been reports of Champix causing memory loss, although the exact mechanism behind this is not yet fully understood. If your husband is experiencing symptoms such as short-term memory loss, changes in motor skills, and speech problems, and these symptoms began after he started taking Champix, it is possible that the medication may be the cause. However, it is important to note that there could be other underlying causes for these symptoms, and a thorough medical evaluation is necessary to determine the root cause. If Champix is found to be the cause of your husband s symptoms, stopping the medication may reverse some of the effects. However, the extent to which the damage can be reversed may depend on the severity and duration of the symptoms. It is important to speak with your husband s healthcare provider about any concerns you have regarding his symptoms and his medication. They can provide guidance on the best course of action, including whether it is safe to continue taking Champix or if an alternative treatment would be more appropriate. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Diwashish Biswas, Internal Medicine Specialist