Please tell me can drinking too much coffee cause problems?

Depends on person: Some people drink enormous amounts of coffee, or otherwise consume large amounts of caffeine with no apparent issues, while other people can't sleep at night if they have one cup in the morning. For most people, 2-3 cups of coffee causes no problems, but some people are more sensitive. Caffeine can cause insomnia, anxiety, tremor, irritability, and if stopped suddenly severe headaches.