I had a colysystectomy four weeks ago but still feellightheaded and weak. all tests came back negative for infection. could it be anesthesia complications?

Unlikely: It sounds more like your body is trying to get used to living without a gallbladder. Are you following all the post op diet instructions?

Not related: Chlolecystectomy now days if done laparascopically is far less invasive than open. Recovery time is better, yet that period of time can vary from patient to patient, especially after age 50. If you are also still taking pain medication this can also be causing your symptoms. Make sure your are hydrated well and eating a regular diet. The anesthesia used for this surgery has been eliminated.

Unlikely: The medications used for anesthesia go away within a few days. The medications that you may be taking fro pain control, that is narcotics, are more likely to be a cause of your symptoms. Please talk to your surgeon if this persists.