As long as the skin has not been cut, onion is an effective cure for bruises, and it is something most people have in their homes. Onions contain a compound called Alicen which is responsible for making you tear up when you cut into an onion. The Alicen is also responsible for stimulating the lymphatic flow and pushing away the excess blood from collecting below the skin. There are two ways you can use onion on your bruises. First, you can cut up the onion, place it onto the bruise and use gauze to hold it in place for up to fifteen minutes. Alternatively, you can dip onion slices in apple cider vinegar and use it to gently rub the bruised area.