Caffeine is a stimulant found in some beverages, including many different sodas, coffee and certain teas. Caffeine is also available in tablet form and may be purchased over the counter. Although caffeine is easily obtainable, this compound does have different side effects that may cause serious health problems.
Caffeine may cause irritation of the gastrointestinal system in men. In large quantities, caffeine can irritate the stomach, possibly resulting in nausea and vomiting. In some men, this irritation may also cause diarrhea. These side effects are generally temporary, however, and go away once the caffeine has been metabolized or excreted from the body.
Caffeine acts as a stimulant, which means it increases activity within the central nervous system. In men, caffeine may cause feelings of increased energy and concentration. In higher doses, caffeine may also cause a "jittery" feeling and result in muscle tremors. Moderately high quantities of caffeine may also lead to a condition known as caffeinism, Drugs.com reports. Caffeinism is marked by restlessness, anxiety and difficulty sleeping. This condition resembles anxiety disorder, and in men the restlessness may take the form of agitation or increased aggressive behavior. Men who have problems with anxiety or panic attacks may have their symptoms exacerbated by caffeine. In addition, chronic heavy use of caffeine has been linked to depression. In high doses, caffeine may cause confusion, convulsions, hallucinations and difficulty breathing, according to MedlinePlus.
Caffeine acts as a diuretic, which means that it increases a man's urine production. The urine is often diluted and may be clear due to the increase in volume. The increased urine output may cause a brief decrease in a man's body weight, according to MayoClinic.com, though this weight loss is temporary and will disappear once the body is able to correct its fluid balance. Because caffeine increases urine output, it may exacerbate dehydration, resulting in feelings of increased thirst and, in severe cases, fatigue or dizziness.
MayoClinic.com reports that the caffeine in about 2 to 3 cups of coffee increases systolic blood pressure 3 to 14 mm Hg and increases diastolic blood pressure 4 to 13 mm Hg. According to RxList, caffeine causes other cardiovascular side effects such as tachycardia, which is an increased heart rate, and an increased stroke volume, which means that the heart pumps unusually hard.