Who among us has never had a nosebleed? Whether a dab of blood on a tissue or a terrifying flood, a nosebleed can arise from many causes: dry winter air, colds, injuries, or the common if unsavory habit of picking one's nose. In many cases, no cause can be identified with certainty.

Sometimes nosebleeds arise more frequently because of faulty or weak collagen, a strengthening protein present in blood vessel walls and the surrounding connective tissue. Collagen problems may lead to nosebleeds in people who take corticosteroids and those with a condition called "fragile capillaries." Corticosteroids, including nasal steroids used for allergies, can thin the collagen in the mucous membranes lining the nose. In fragile capillaries, weak or defective collagen in blood vessel walls may contribute to bleeding. People with such collagen problems may have problems with bleeding gums, heavy menstrual periods, and bruising in addition to nosebleeds.

Rarely, the cause of nosebleeds and other bleeding lies in the blood itself. Anything that reduces blood clotting may lead to nosebleeds. Drugs such as warfarin (Coumadin) or heparin, or regular use of aspirin, decrease the blood's tendency to clot. Caution: if you are taking such medications and begin to experience nosebleeds, talk to your doctor. Even natural substances such as ginkgo, policosanol, high-dose vitamin E, and garlic may increase the tendency to bleed.

Conventional treatments for nosebleeds include various maneuvers for stopping acute bleeding, followed by the diagnosis and treatment of any underlying problems. Sometimes a physician can prevent future nosebleeds by cauterizing the blood vessel responsible.

One supplement that may help prevent nosebleeds is citrus bioflavonoids. Bioflavonoids (or flavonoids) are plant substances that bring color to many fruits and vegetables. Citrus fruits are a rich source of bioflavonoids, including disomin, hesperidin, rutin, and naringen.

A double-blind, placebo controlled studyof 96 people with fragile capillaries found that a combination of the bioflavonoids diosmin and hesperidin decreased symptoms of capillary fragility, such as nosebleeds and bruising.1 In this 6-week trial, participants—41% of whom had problems with nosebleeds—took 2 tablets daily of the bioflavonoid combination or placebo. Those who received bioflavonoids had significantly greater improvements in both their symptoms and their capillary strength compared to those taking placebo. Unfortunately, the researchers did not state how much the nosebleeds improved.

For more information, including dosage and safety issues, see the full citrus bioflavonoids article.