I'll admit that I got a bad case once.
My doctor said that part of it is genetic, that some people just have weak vascular plumbing. He also noted many of things that others have said.
But he also said that one of the biggest problems was when people read on the toilet. Sitting on the toilet will strain the hell out of those blood vessels no matter what, so finish that chapter after you finish your business. Sounds funny, but makes sense.
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