When the iron tablet is taken for the first time, the body may find it little difficult to digest and you may have symptoms such as stomach ache and nausea. However if we take the iron tablet after food, the absorption will be little low but stomachache and nausea will not occur. These side effects disappear once you take the tablet regularly for a few weeks as the body adjusts to the iron tablets. Some people may complain about black stools, but they are totally harmless. The body takes the iron it needs and the extra iron comes out of body through faces. To avoid any side effects you should never take the tablet on an empty stomach. Taking any vitamin or nutrient is never restricted during an illness. In fact it helps you to recover fast from your illness by improving immunity of the body.