If you are genuinely ill (and not hungover, or tired from staying up too late watching TV !) then GO HOME. You'll not be doing anyone any favours staying at work as you're not functioning to your best ability and more likely to make mistakes, you will be passing your germs onto your colleagues therefore you should feel obliged to go home. Everyone always feels guilty for the wrong reasons....but no-one will thank you at the end of the day. Get home, get to bed, or see your Dr and don't go back until you feel 100% xx