Although everyone’s system moves at a different pace, going for longer than 3 days without a bowel movement is considered too long. Your body needs to remove waste in order to stay healthy. If your body is hanging onto that waste for too long, you essentially have rotting matter piling up in your system, which is never a good thing.
If you have to strain, or it becomes uncomfortable to pass a bowel movement, constipation is the likely cause. Drinking extra fluids, and introducing more fruits and vegetables into your diet are two ways to help things along without turning to harsher methods. There are also several types of tea that use calming herbs to help you go. If your constipation reaches a point where you are throwing up, go see your doctor immediately.