Many people drink more than the daily recommended intake of caffeine.  Healthy adults can drink up to 400 mg of caffeine a day (about 4 cups of homemade drip coffee) without negative effects like headaches, drowsiness, anxiety and nausea, according to a recent study in the Journal of Food Science

A Grande Starbucks Coffee contains 330 mg of caffeine.

A 5-Hour Energy Shot (2 oz.) contains 207 mg of caffeine.

A Grande Starbucks Latte contains 150 mg of caffeine.

Homemade drip coffee (8 oz.) contains 100-200 mg of caffeine.

A medium McDonald's Coffee (16 oz.) contains 100 mg of caffeine.

A small Red Bull (8.4 oz.) contains 76-80 mg of caffeine.

A Lipton Black Tea contains 55 mg of caffeine.

A Lipton Green Tea contains 45 mg of caffeine.

Espresso (1 oz.) contains 40-75 mg of caffeine.

A can of Coke or Diet Coke contains 35 mg of caffeine.

A Grande Starbucks Decaf Coffee contains 12 mg of caffeine.