Hi Thanks for posting your query on HCM. Boric acid suppositories are considered safe for treating chronic yeast infections involving vagina. However, they can cause skin irritation or a burning sensation in the vagina. You might have missed some of the pills or taken the placebo tablets (without actual containing hormones) that could have been responsible for the heavy bleeding. You need to consult a gynecologist for further evaluation to detect the cause of excessive vaginal bleeding. Hope this answers your query. Take care.