Excess weight can make it more challenging to safely administer anesthesia, introducing potential problems with locating veins, determining dosage and ensuring you get enough oxygen.

Some anesthesia side effects are more likely to occur in elderly patients, and aging-related health problems such as high blood pressure, clogged arteries and lung disease can increase risk.

Smoking can increase the risk of anesthesia-related complications during or after surgery. But quitting smoking before the procedure can help.

Millions of people in the United States are affected by sleep apnea — millions more don’t realize they have it — and anesthesia can make the condition worse.

Certain health conditions increase the potential for anesthesia awareness — recalling some aspects of the surgery while under general anesthesia, but usually without feeling pain.