Injections of small doses of the blood thinners unfractionated heparin or low-molecular-weight heparin can prevent VTE. Because many hospitalized patients have VTE risk factors, many hospitals routinely give patients blood thinners to prevent VTE. However, these medications can cause bleeding. Bleeding due to these medications is usually mild, through the gastrointestinal tract or skin wounds. However, it can be severe and occur in a critical organ, such as the brain. Another way to prevent VTE is to put mechanical devices that squeeze the lower part of patients' legs to prevent clots from forming. These devices are uncomfortable, can cause skin breakdown, and might have the unwanted effect of keeping patients in bed.