Yes, you can drink four cups of coffee a day, assuming you can tolerate the caffeine, meaning that this amount doesn’t produce unwanted side effects such as irritability, insomnia, or stomach upset. In fact, some studies have shown that four to five cups of coffee per day may be just about the right amount to drink.
In 2012, a study published in the New England Journal of Medicine looked at the connection between coffee drinking and the risk of dying for over 400,000 individuals aged 50-71 during the 12-13 year study period. The results showed drinking 4-5 cups of coffee a day had the lowest risk of death.