Gastrointestinal (GI) perforation: Treatment with Avastin can result in the development of a serious side effect called GI perforation, which is the development of a hole in the stomach, small intestine, or large intestine. In clinical trials, this event occurred in more people who received Avastin than in the comparison group (2.4 percent to 0.3 percent). In some cases, GI perforation resulted in fatality. Avastin therapy should be permanently stopped if GI perforation occurs.Surgery and wound healing problems: Treatment with Avastin can lead to slow or incomplete wound healing (for example, when a surgical incision has trouble healing or staying closed). In some cases, this event resulted in fatality. Surgery and wound healing problems occurred more often in people who received Avastin than in the comparison group. In a controlled clinical trial, in patients with metastatic colorectal cancer who had surgery during the course of treatment, the incidence of wound healing complications, including serious and fatal complications, was 15 percent for patients who received Avastin and four percent for patients who did not receive Avastin. Avastin therapy should not be started for at least 28 days after surgery and until the surgical wound is fully healed. The length of time between stopping Avastin and having voluntary surgery without the risk of wound healing problems following surgery has not been determined. Treatment with Avastin should be stopped at least 28 days before voluntary surgery and in people with wound healing problems following surgery that require medical treatment. Treatment with Avastin should be stopped in patients with slow or incomplete wound healing. Severe bleeding: Treatment with Avastin can result in serious or fatal bleeding, including coughing up blood, bleeding in the stomach, vomiting of blood, bleeding in the brain, nosebleeds and vaginal bleeding. These events occurred up to five times more often in people who received Avastin compared to patients who received only chemotherapy. Across cancer types, 1.2 percent to 4.6 percent of people who received Avastin experienced severe to fatal bleeding. People who have recently coughed up blood (greater than or equal to a half teaspoon of red blood) or have serious bleeding should not receive Avastin. Treatment with Avastin should be permanently stopped if serious bleeding occurs. In clinical trials for different cancer types, there were additional serious and sometimes fatal side effects that occurred in more people who received Avastin than in those in the comparison group. The formation of an abnormal passage from parts of the body to another part (non-GI fistula formation) was seen in 0.3 percent or less of people. Severe to life-threatening stroke or heart problems were seen in 2.6 percent of people. Too much protein in the urine that led to kidney problems was seen in less than one percent of people. Additional serious side effects that occurred in more people who received Avastin than those in the comparison group included severe to life-threatening high blood pressure, which was seen in five percent to 18 percent of people, and nervous system and vision disturbances (reversible posterior leukoencephalopathy syndrome), which was seen in less than 0.1 percent of people. Infusion reactions with the first dose of Avastin were uncommon and occurred in less than three percent of people, and severe reactions occurred in 0.2 percent of people. Avastin can cause fertility issues for women. Avastin could cause a woman’s ovaries to stop working and may impair her ability to have children.