“If it’s a viral cause, you have to maximise your immune system,” Cohen warns. “Things like sleep. If you’re rundown, if you’re stressed – and that can be emotional stress as well as physical stress – if you’re not getting enough sleep, if you’re not eating well and if you’re not drinking enough [water] and you’re dehydrated, they can all make a cough worse or prevent it from getting better.”
Source: https://startsat60.com/health/big-issues/best-way-treat-coughs