First, it should be noted that eNotes answers are exclusively for study purposes and are not intended as medical advice. If you have a medical question or problem, you should consult your healthcare provider.
The recommended maximum quantities of caffeine vary with your age and condition. Children should consume no more than 100 mg. of caffeine a day. Pregnant women should also restrict caffeine intake to under 300 mg. a day. The elderly and people with heart and other medical conditions that might be affected by caffeine intake may be advised to restrict or eliminate caffeine. For healthy adults, 300-400 mg. a day is probably safe, although if consumed within 5 hours of bedtime it may interfere with sleep. Avoid consuming caffeine along with other stimulants.