Caffeine Quiz: Test Your Medical IQ

Caffeine can cause some mild physical dependence, but it is not technically addictive. It is a central nervous system stimulant that is not considered an addictive drug because it does not affect a person's physical health or cause the same drug-seeking behaviors as alcohol or street drugs. A mild physical dependence on caffeine may cause some withdrawal symptoms when it is stopped, such as headaches, fatigue, and irritability.

Moderate caffeine consumption may reduce your risk for developing diabetes, liver disease, gallstones, and Parkinson's disease. It may also help reduce headaches and the risk for certain heart related illnesses. That said, caffeine is generally not recommended to reduce the risks for these conditions, as caffeine can also cause health problems such as decreased bone density, increased blood sugar levels, dehydration, and poor sleep.

In general, doctors recommend women reduce caffeine consumption when pregnant. Caffeine is a stimulant which can increase your heart rate, something that should be avoided during pregnancy. Caffeine also crosses the placenta and while an adult woman can handle the caffeine, a developing baby may not be able to. Studies have shown caffeine can cause birth defects, premature delivery, and miscarriage. Moderate levels of caffeine (150 – 300 mg) may be ok. Consult your doctor.

Caffeine passes into breast milk in small amounts. The American Academy of Pediatrics states a cup of coffee is unlikely to cause harm to a nursing baby, but too much caffeine can cause problems including poor sleep, irritability, nervousness, and poor feeding. If you notice these symptoms in your baby, it may be a sign to cut back on your caffeine intake.

How much caffeine is in a cup of coffee? That depends on how the coffee is brewed, the type of coffee bean used, and how much coffee is prepared. An average 8 oz. cup of coffee contains 95 mg caffeine, but a 20 oz. Starbucks Blonde Roast Venti can have upwards of 475 mg caffeine. Even the same size and type of coffee ordered from the same place can vary in caffeine content. Florida researchers placed the same order at the same coffee shop for 6 days in a row and found the caffeine content varied, from 259 mg to 564 mg.

About 99% of the caffeine you consume is in your bloodstream within 45 minutes of drinking a cup of coffee, but the effects of that caffeine can up to five to six hours. Some people are much more sensitive to caffeine and these effects may last even longer.

Caffeine is added to many headache and migraine drugs because it can help the body absorb these medications more quickly. In fact, caffeine added to a combination of acetaminophen (Tylenol) and aspirin, the pain relievers are 40% more effective. Because the pain relievers can work faster and more efficiently, patients can take less medication to relieve symptoms.

Caffeine is often added to skin-care products for its anti-aging properties. Caffeine is stimulates blood flow and contains anti-oxidants which are reported to smooth skin and reduce the appearance of fine lines and wrinkles.

Caffeine actually has a greater effect on men than on women. A 2008 study found that men started feeling the effects of caffeine in as little as 10 minutes after consumption. Decaffeinated beverages produced more alertness in women.

As we age, our sensitivity to caffeine increases. It may improve cognitive functioning in the elderly, particularly in women.

Caffeine is a stimulant, and its effects can be similar to the jitteriness or nervousness people with anxiety disorders may experience. It may even trigger an anxiety or panic attack. The National Institute of Mental Health recommends people with anxiety disorders avoid caffeine because it can aggravate symptoms.

Caffeine cannot sober you up when you're intoxicated. In fact, caffeine may make it harder for you to tell just how drunk you are which can lead to risky behaviors such as driving while under the influence.

Caffeine does have a mild diuretic effect, but in general will not contribute to dehydration when ingested in beverage form. Those who do not consume caffeine on a regular basis will experience more of a diuretic effect than those who drink caffeinated beverages regularly.

Caffeine overdose is rare, but it can happen and often involves large amounts of caffeine ingested in pill or powder form rather than in beverages. The amount of caffeine needed to overdose depends on a person's size, gender, and age, as well as individual tolerance to caffeine. Doses of 10 grams (equal to about 85 cups of coffee) are potentially fatal in adults.

There is no limit to the amount of caffeine contained in energy drinks. Because caffeine is not a nutrient, manufacturers are not required to list amounts on their product labels. Data suggests healthy adults can consume up to 400 mg caffeine daily with no ill effects – that's about 4 cups of coffee or 10 glasses of cola. Some energy drinks may have more than 200 mg caffeine per serving. Excess caffeine can cause jitteriness, migraines, insomnia, irritability, frequent urination, restlessness, and rapid heartbeats.