According to Drugs.com, common side effects associated with the use of Daflon include upset stomach, mild diarrhea and nausea. Patients should talk with their physicians if these problems persist or become overly bothersome. Serious side effects of Daflon include allergic reactions, such as rash, hives, difficulty breathing, swelling of the mouth, chest tightness, and numbness or tingling of the skin. These severe side effects require immediate medical attention.
Dr. Ray Sahelian explains that Daflon is an entirely natural oral supplement that is typically used to treat chronic venous disease and hemorrhoids. Containing 10 percent flavonoids as hesperidan and 90 percent diosin, it is a micronized purified flavonoid fraction.
According to Wikipedia, Daflon is particularly useful for treating accute hemorrhoid attacks. The common dosage of Daflon for treating hemorrhoids is six tablets a day for four days and then four tablets a day for the next three days. The dosage for treating venous insufficiency is two tablets per day.
WebMD notes that diosin is useful for treating blood vessel disorders, such as poor circulation in the legs, varicose veins and bleeding in the gums or eyes. The site states that using diosin for a period of up to three months is safe for most people but advises against using the supplement for more than three months without medical supervision.