This is the reason why many experts warn that you shouldn’t drink coffee in the morning on an empty stomach immediately after waking up.
The main reason is because the coffee is going to increase the levels of cortisol and the body needs a long time to balance its normal state.
Cortisol is a hormone that controls our biological clock and the aptitude to remain awake.
Consuming coffee on an empty stomach is going to increase the levels of acid in the stomach and that will cause vomiting and abdominal distension.
According to this, consuming coffee on an empty stomach immediately after waking up can be really bad for you.
You must have breakfast before having coffee in the morning.
But, if you cannot have breakfast and you cannot start the day without a cup of coffee, then you must add a little milk or cream in your coffee.
This will help you reduce its harmful effects./source