No good until that first cup of coffee in the morning? Need a soda in the afternoon to keep going? Have trouble falling asleep in the evening?

Uh oh! Maybe you should eliminate caffeine.

And then again, maybe not.

How Bad Is It?

Caffeine, a mild stimulant, interacts with the brain and nervous system much like amphetamines. For many, it helps us concentrate and pay better attention to tasks at hand. It "wakes us up" in the morning and keeps us alert. Caffeine occurs naturally in a number of seeds and plants and is most often associated with coffee and tea.

Some people are more sensitive to caffeine than others and so the decision to eliminate or curtail it is usually a personal one. Many folks drink two or three cups of coffee a day--which is considered average--with very few, if any, deleterious effects.

On the other hand, a lot of people believe caffeine interferes with sleep, makes then edgy, increases restlessness, anxiety and depression, causes nausea and vomiting, and makes them shake. All the above can be true for some but not for all.

Caffeine can also cause your heart to beat rapidly and interfere with maintaining your blood pressure if you suffer from hypertension. It causes calcium loss in some instances and therefore older people are often advised to cut way back.

Caffeine interacts negatively with some drugs, which means it’s always a good idea to discuss this possibility with your doctor or pharmacist. It also shows up in a lot of over-the-counter remedies, such as cold pills and cough medicine, and so anyone concerned should read the labels.

Some women worry caffeine makes it hard to conceive and contributes to problems ranging from birth defects to low-birth weight. There is not much evidence that any of this is true when low amounts of caffeine are consumed, but these concerns should be discussed with a doctor.

Caffeine is mildly addictive, although not in the way other drugs are. It does not interfere with daily life or cause anyone to hock the family jewels for their next fix. Still, stopping it abruptly can cause a few days of headaches, anxiety, irritability and fatigue.

Finally, kids should stay clear of caffeine. A little does no harm, but children and adolescents often are sensitive to it and it can make them anxious or grumpy. Also, most kids consume caffeine in sweetened sodas, teas and sports drinks, which means they are getting a lot of sugar—which is never a good idea.

How Much Is There?

The amount of caffeine in different drinks and foods varies. Soda has set amounts, but not all coffees and teas are alike and so the caffeine count is never constant.

A 12-ounce can of Coca Cola has 35 milligrams (mg) of caffeine, while the same amount of Diet Coke has 47 mg. Mountain Dew, regular or diet, provides 71 mg of caffeine.

Sports drinks tend to boost the caffeine count, so that eight and a half ounces of Red Bull boasts 80 mg and eight ounces of Rip It has 100 mg.

Most people get their caffeine from coffee. A typical eight-ounce cup of brewed, drip coffee has between 75 and 200 mg of caffeine, with the average being 125 to 130 mg.

Brewed black tea can have as little as 40 mg and as much as 120 mg of caffeine, although the average cup of tea contains about 50 mg.

Even decaffeinated brews have a little caffeine; the decaffeinating process does not eliminate all caffeine. Eight ounces of decaffeinated coffee has between two and 12 mg and averages about five. The same amount of decaf black tea has between two and 10 mg, while decaf green tea weighs in between one and four milligrams.

How Much Is Too Much?

While the decision to eliminate caffeine from your diet is a decision you have to make for yourself, in some instances it’s a good idea to discuss it with your doctor. This is particularly important if you are or plan to get pregnant, if you have high blood pressure, or if you deal with depression or anxiety.

Caffeine is absorbed and then expelled relatively quickly by the body. It takes about six hours for half of it to leave our systems and after 10 hours, nearly all is gone. This means that cup of coffee you drink in the morning won’t impact your slumber later that night. It also means those sensitive to caffeine should cut if off at least six hours before retiring.

Both the FDA and the American Medical Association say that moderate amounts of caffeine a day are “generally recognized as safe.” They classify intake this way:

Low to moderate amounts of caffeine: 130 to 300 mg a day

Moderate amounts: 200 to 300 mg a day

High amounts: 400 mg and higher

Heavy or excessive amounts: 6,000 mg

If you drink two or three cups of coffee, three or four cups of tea, or even three or four sodas a day, caffeine is not likely to affect you. (Although, if you drink regular soda or sweeten your hot beverage, you should be concerned about the amount of sugar you are consuming.)

If you drink six, seven or more cups of coffee or tea a day, you may want to think about kicking the habit — or at least cutting back.