The most common cause of external hemorrhoids is repeated straining while having a bowel movement. Hemorrhoids develop when the veins of the rectum or anus become dilated or enlarged and can be either internal or external.
The veins around your anus tend to stretch under pressure and may bulge or swell. Swollen veins (hemorrhoids) can develop from increased pressure in the lower rectum due to: Straining during bowel movements. Sitting for long periods of time on the toilet.
