The sufferer is tremulous and loses his self command: he is subject to fits of agitation and depression. He has a haggard appearance. As with other such agents, a renewed dose of poison gives temporary relief, but at the cost of future misery.
Sir T C Allbutt and H.D. Rolleston, A system of medicine, l909

The side-effects pass almost unnoticed nowadays. It is the most used psychoactive substance on the planet. The average adult consumption is about 200 mg a day, mostly from coffee.

Caffeine acts quickly on the brain. It triggers almost the same hormonal cascade as a stressful event and with the same after effects.

It increases adenosine by blocking its degradation which increases wakefulness and alertness and decreases reaction times. It stimulates the adrenal glands to release adrenaline which tightens the muscles and mobilises the liver to release sugar for energy.

Caffeine, like amphetamines, heroin and cocaine increases dopamine by slowing its re-uptake. this activates pleasure centres and causes some relaxation and causes some kinds of blood vessels to open.

Physiological effects last up to 45 minutes and include increased heart rate, temperature, urination, alertness and gastric acid secretion.

The half life of caffeine in the body is 2-6 hours (though its metabolism varies with liver disease, medications, smoking etc).

Major withdrawal symptoms usually begin 12 to 24 hours after terminating caffeine intakes. Peak withdrawal intensity is usually 20 to 48 hours after abstinence. Withdrawal might last between 2 days and 1 week, although longer durations have been claimed.

Many are unaware of their dependence because withdrawal symptoms can take up to 5 days to appear and small doses of caffeine from other sources like chocolate can suppress them.

Withdrawal symptoms may occur on weekends or holidays when caffeine intake is less.

headache – often growing gradually and diffuse, sometimes throbbing and severe, usually in the temples, occasionally at the back of the head or around the eyes. A mild muscular headache often follows.


anxiety, nervousness





fatigue, drowsiness, apathy


ringing in the ears


inability to concentrate

Impairment in psycho motor, vigilance and cognitive performances

flu-like symptoms -- (e.g. nausea/vomiting, muscle aches/stiffness, runny nose, hot and cold spells, heavy feelings in arms or legs)

Caffeine is very addictive. Most use is to avoid the minor withdrawal symptoms that occur after a few hours abstinence.

The smell of coffee is a powerful reminder of the relief from withdrawal symptoms that awaits. This powerful trigger bypasses the thinking part of the brain to make the taking of coffee almost a reflex.

health effects
Reduction or elimination of caffeine intake is advised for a wide range of diseases.

Caffeine is a diuretic which can cause dehydration and loss of essential nutrients, including potassium, magnesium, zinc and vitamin C. It leeches calcium from the body and so increases the incidence of loss of bone mass and Osteoporosis. It depletes Vitamin B1, inositol, Biotin, potassium, zinc, and can inhibit calcium and iron assimilation.

Long term or excessive caffeine use causes much the same problems as stress

poor concentration and reduced memory and cognition

Nervousness, anxiety, agitation, panic attacks, depression

irritability, episodes of rage



lowered immune response and the harm that results

reduced cerebral blood flow)

insomnia – extreme use can lead to sleep deprivation and psychotic episodes

dizziness, bed wetting


blood flow to the stomach slows

gastroesophageal reflux

upset stomach, GI irritation, ulcers, peptic ulcer disease



raised blood cholesterol,

stiffened arteries

irregular or increased heartbeat

high blood pressure

Increase palpitations and heart irregularities.

fibrocystic breast disease





chronic fatigue

fertility and conception disorders and complications of pregnancy and childbirth.

crosses the placenta

gets into the breast milk.

sudden caffeine withdrawal can kill newborns.

miscarriage, prematurity and stillbirth.

damages chromosomes at very high dosage levels

moderate consumption may reduce fertility by damaging sperm.

benign breast disease and prostate problems.

can interfere with DNA replication. birth defects.

cancer. increase the cancer-causing effect of some substances..

bladder cancer has been linked to a nicotine and caffeine combination.

prostrate enlargement and pancreatic cancer.


400 billion cups of coffee are consumed annually. It is the largest agricultural commodity in the world and the third leading commodity after petroleum and strategic metals using 70 million acres of the most fertile land. Rain forest is being destroyed to plant coffee farms. It is labour-intensive.

It is the most heavily sprayed of all crops. Toxic chemicals are used in many stages of growing and marketing coffee. There are few if any pesticide restrictions or regulations where it is grown. It has anti-nutrient properties and almost no nutritional value.

Its rancid oils and the irritating acids are further hazards. Food industry financed research and advertising promotes coffee as safe and even beneficial. Regulatory agencies tend to go along with this.

King Charles II of England tried to ban Coffee houses as coffee produced disorderly conduct but public outcry kept them open.

Tea has generally less caffeine.

milligrams of caffeine




coffee (8-oz. cup) varies with brewing, variety, brand



brewed, drip method


65 - 120



60 - 85



2 - 4

espresso (1 oz. cup)



30 - 50

teas (8-oz. cup)



brewed, major u.s. brands


20 - 90

brewed, imported brands


25 -110

weak tea


8 - 20



24 - 31

iced (8-oz. glass)


9 - 50

cola drinks (250ml)



some soft drinks (8 oz.)


20 - 40

cocoa beverage (8 oz.)


3 - 32

chocolate milk beverage (8 oz.)


2 - 7

milk chocolate (1 oz.)


1 - 15

dark chocolate, semi-sweet (1 oz.)


5 - 35

200gm chocolate bar


20 - 60

chocolate (1 oz.)



chocolate-flavoured syrup (1 oz.)



guarana drinks


up to 250

red bull (250ml can)




a wide range of drugs including diet pills and “natural” alternative medications contain caffeine sometimes under names like guarana.