If you’ve had diarrhoea, it’s important that you rehydrate yourself. An upset stomach can cause your body to lose fluids which is why rehydration medicine is useful. Rehydration products are available as sachets or tablets that are mixed with water to aid rehydration. Rehydration remedies include drinking fluids such as water and eating bland foods. Rehydration treatment can help restore electrolyte levels lost through a stomach bug.