All about caffeine you need to know are here

All you need to know about caffeine

Caffeine is a white, bitter crystalline alkaloid derived from coffee or tea. It belongs to a class of compounds called xanthones, its chemical formula being 1,3,7-trimethylxanthine. Caffeine is classified together with cocaine and amphetamines as an analeptic, or central nervous system stimulant. Coffee is the most abundant source of caffeine, although caffeine is also found in tea, cocoa, and cola beverages as well as in over-the-counter and prescription medications for pain relief.Caffeine-related disorders are often unrecognized for a number of reasons:
Caffeine has some legitimate medical uses in athletic training and in the relief of tension-type headaches. .
Caffeine is less likely to produce the same degree of physical or psychological dependence as other drugs of abuse. Few coffee or tea drinkers report loss of control over caffeine intake, or significant difficulty in reducing or stopping consumption of beverages and food items containing caffeine.
The symptoms of caffeine intoxication are easy to confuse with those of an anxiety disorder.

Pharmacological aspects of caffeine

An outline of the effects of caffeine on the central nervous system (CNS) and other organ systems of the body may be helpful in understanding its potential for physical dependence. When a person drinks a beverage containing caffeine (or eats coffee-flavored ice cream), the caffeine is absorbed from the digestive tract without being broken down. It is rapidly distributed throughout the tissues of the body by means of the bloodstream. If a pregnant woman drinks a cup of coffee or tea, the caffeine in the drink will cross the placental barrier and enter the baby's bloodstream.
When the caffeine reaches the brain , it increases the secretion of norepinephrine, a neurotransmitter that is associated with the so-called fight or flight stress response. The rise in norepinephrine levels and the increased activity of the neurons, or nerve cells, in many other areas of the brain helps to explain why the symptoms of caffeine intoxication resemble the symptoms of a panic attack .
The caffeine content of various food items and medications is as follows:

Brewed coffee, 8-oz cup: 135–150 mg
Instant coffee, 8-oz cup: 95 mg
Powdered cappuccino beverage, 8-oz cup: 45–60 mg
Tea brewed from leaves or bag, 8-oz cup: 50 mg
Iced tea from mix, 8-oz glass: 25–45 mg
Snapple iced tea, 8-oz glass: 21 mg
Mountain Dew, 8-oz glass: 38 mg
Caffeine can produce a range of physical symptoms following ingestion of as little as 100 mg, although amounts of 250 mg or higher are usually needed to produce symptoms that meet the criteria of caffeine intoxication.

The symptoms of caffeine intoxication include:

restlessness
nervousness
excitement
insomnia
flushed face
diuresis
gastrointestinal disturbance
muscle twitching
talking or thinking in a rambling manner
tachycardia
periods of inexhaustibility
psychomotor agitation
People have reported ringing in the ears or seeing flashes of light at doses of caffeine above 250 mg. Profuse sweating and diarrhea have also been reported. Doses of caffeine higher than 10 g may produce respiratory failure, seizures , and eventually death.
Side effects and complications
High short-term consumption of caffeine can produce or worsen gastrointestinal problems, occasionally leading to peptic ulcers or hematemesis
Drug interactions
Caffeine is often combined with aspirin or acetaminophen in over-the-counter and prescription analgesics (pain relievers). It can also be combined with ibuprofen. On the other hand, certain groups of drugs should not be combined with caffeine or taken with beverages containing caffeine. Oral contraceptives, cimetidine (Tagamet), mexiletine (Mexitil), and disulfiram (Antabuse) interfere with the breakdown of caffeine in the body. Caffeine interferes with the body's absorption of iron, and with drugs that regulate heart rhythm, including quinidine and propranolol (Inderal). Caffeine may produce serious side effects when taken together with monoamine oxidase inhibitors or with certain decongestant medications.

Diagnosis

Diagnosis of a caffeine-related disorder is usually based on the patient's recent history, a physical  examination, or laboratory analysis of body fluids. In addition to medical evidence, the examiner will rule out other mental disorders, particularly manic episodes, generalized anxiety disorder , panic disorder , amphetamine intoxication, or withdrawal from sedatives, tranquilizers, sleep medications, or nicotine. All of these disorders or syndromes may produce symptoms resembling those of caffeine intoxication. In most cases, the temporal relationship of the symptoms to high levels of caffeine intake establishes the diagnosis.
Treatments
Treatment of caffeine-related disorders involves lowering consumption levels or abstaining from beverages containing caffeine. Some people experience mild withdrawal symptoms that include headaches, irritability, and occasionally nausea, but these usually resolve quickly.
Prognosis
With the exception of acute episodes of caffeinism, people recover from caffeine intoxication without great difficulty.
Prevention
Prevention of caffeine-related disorders requires awareness of the caffeine content of caffeinated beverages, OTC drugs, and other sources of caffeine; monitoring one's daily intake; and substituting decaffeinated coffee, tea, or soft drinks for the caffeinated versions of these beverages.