Marvel comics writer Mark was raced to hospital after his temperature soared to 103 and he developed extreme flu-like symptoms.
Mark, of Glasgow, said: "I went off sick the first week of December and thought I had a heavy cold or flu. My temperature was a consistent 103F and I was awake all night shivering.
Doctors finally discovered Mark was suffering a severe reaction to his medication for Crohn's, which causes agonising inflammation of the digestive tract.
"They found out I had a bad reaction to pills you take if you have Crohn's Disease - really powerful drugs called azathioprine.
"They've kept Crohn's at bay - I've only had one flaremy whole life - but this is the second time I've had a nasty side effect."
Dad-of-one Mark - who turned 39 on Christmas Eve - added: "They tookme off them, sent me home and I slept through my birthday and Christmas.
"I'm feeling a little stronger but I need to take January off for a full recovery."
