Ingesting CBD products in large quantities has little to no negative side effects. People have consumed more than 1,500 milligrams of CBD daily with no adverse effects. If you enjoy CBD coffee with 10 milligrams of CBD per serving, you could theoretically have 150 cups in a day. However, caffeine is not as innocuous as CBD. Experts recommend consuming no more than 400 milligrams of caffeine in 24 hours. The FDA states that 400 milligrams of caffeine a day can constitute a healthy adult diet, but 600 milligrams is too much.