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Vitamin C and K deficiencies can also be responsible for petechial rash or purpura which look like flat tiny red, brown, or purple spots on the skin (petechiae) or larger ones (purpura).
Side effects of some medicines or supplements
Certain medications and supplements can cause the blood to thin and result in random bruising on the body. If you are taking blood-thinning medications, you may find that even a slight knock on your leg or arm can easily cause bruising.
According to doctors from the Mayo Clinic, aspirin, some antibiotics, and anticoagulant medications can cause clotting problems. This can result in random bruising or larger bruises from trauma to the skin.3
Also, supplements like ginkgo biloba, ginger, turmeric, St John’s Wort have blood-thinning properties and may make you bruise easily. Before taking any supplements that thin the blood, you should speak to your health care provider if you are already taking medication to prevent blood clots.
That is one reason why some people shouldn’t take turmeric regularly for medicinal purposes. Ginger should also be used with care if you take medication to thin the blood.
Hereditary conditions
Sometimes unexplained bruising on your legs or body is because of hereditary factors. Dr. William Blahd on WebMD says that if your parents bruised easily, there is a greater chance that random bruising will affect you as well.7