No, stress is not inevitably harmful to the human body. There are various types of stress but each of them is not harmful. There is positive stress which is good for us. Positive stress is known as eustress which can be psychological, physical, biochemical or radiological. But there is some chronic stress which affects our body and mind negatively. This type of stress is known as distress.
They are the negative stress which we usually get to hear about from people and also sometimes, after hearing disturbing news. Excessive good stress can also affect our body in a negative manner as it drives us overwhelmed. So, be it positive or negative, we should control our stress level to stay healthy.