How big is it ? If, it is big than just a pimple's size, then you need a doctor to lance it and squeeze the toxin ( poison ) out, otherwise it will burst from the inside and it will go in your bloodstream to kill you. First before it gets in your bloodstream, you will be experiencin' high fever, sweat and very sick. That's a sign of toxic buildin' up in boil.
I had one boil before and it was very unpleasant experience for me. The fever was 105 and I was rushed to the hospital to have a doctor to lance it without anthesia ( sp ? ). I wasn't put to sleep. I was fully awake and can feel the pain. Of course, I cried out every time she ( dr. ) squeezed the " poison " out of boil. It was on my butt near the spinal cord. After she frequently squeezed it, the fever went down and I was given a pint of water in my vein ( IV ) to prevent dehydrated. It took about 2 hours to complete before I went home.
She told my ex that I would be dead within 24 hours after she checked a very deep RED spot in boil where there was a pink around it. It could burst anytime within 24 hours and I was lucky to be at the hospital on time.
Boil, cyst, lymph node, and a few are under " cancer ". They are family of cancer's - I think. Cancer ran in my mother's family side.
If, you had this BIG boil and still growin'... don't wait. Go and see your doctor.