Orange Juice. Contrary to what you might think, orange juice is more harmful than beneficial when you have a prolonging cough and sore throat. It could burn the already-inflamed membranes in your throat.
Milk. Drinking milk causes your body to thicken mucus and phlegm, making your throat even more uncomfortable and irritated. If you feel congested and stuffy, skip the milk and drink water instead.
Sweets. The sugar in these sweets weakens your immune system at a time like this.
Eggs. There really isn't anything wrong with eggs per se, but a lot of people feel worse after smelling the aroma. And nobody wants an upset stomach on top of whatever else is making them feel bad.