DIFFICULT TO ANSWER. I ASSUME YOU MEAN HEAVY VAGINAL BLEEDING. THERE ARE SEVERAL VARIABLES TO CONSIDER. HOW MANY DAYS YOU HAVE HAD THIS; YOUR OB HISTORY; MEDICATIONS YOU TAKE; BUT ESPECIALLY IF YOU ARE HAVING OTHER SYMPTOMS OF ANEMIA FROM BLOOD LOSS, SUCH AS LIGHT HEADED, PALE EYES (THE WHITE PART OF EYE) WEAKNESS. AND IF ABDOMINAL PAIN IS A CHANGE, OR IF YOU HAVE ASSOCIATED FEVER. I RECOMMEND TALKING TO YOUR OB/GYN FIRST, BUT IF YOU HAVE SEVERE SYMPTOMS THEN BEST TO BE SAFE AND GO TO THE ER.

WHEN YOU CHANGE 4 LARGE PADS IN ONE HOUR.

I assume you are referring to menstruation?! If you find yourself going through a heavy duty pad in less than an hour, I would go get checked out by your OBGYN. There is no need to go to the ER.

If you have prolonged menstrual bleeding, more than 15 days and/or heavy bleeding (with clots and using more than 5 pads a day), even if for the duration of a regular menses, it is important to seek medical attention. But if bleeding heavily and/or you become weak, dizzy, short of breath, develop palpitations or chest pain, it is important to go to ER or call 911 ASAP.

Feeling lightheaded or short of breath