Caffeine acts as a central nervous system (CNS) stimulant, increasing alertness in people who are tired or sleepy. Caffeine occurs naturally in tea, coffee, cocoa, and chocolate, and is added to many soft drinks. Sometimes caffeine is added to products containing codeine.
Caffeine is freely soluble in pyrrole, tetrahydrofuran; soluble in water, ethyl alcohol, pyridine, acetone, chloroform, ether, benzene; slightly soluble in petroleum ether.
Precautions
You should take special care in taking caffeine if you have any of the following conditions:
anxiety
diabetes
heart disease or irregular heartbeat
high blood pressure
liver disease
panic attacks
peptic ulcer disease or colitis
seizure disorder
thyroid disease
trouble sleeping
an unusual or allergic reaction to caffeine, aminophylline, theophylline, other medicines, foods, dyes, or preservatives
pregnant or trying to get pregnant
breast-feeding
Side effects and overdose
Side effects that may require medical attention:
anxiety or panic reactions
confusion
dizziness, light-headedness, or fainting spells
fast or irregular breathing or heartbeat (palpitations)
muscle twitching
nausea and vomiting
seizures (convulsions)
trembling
Side effects that usually don't require medical attention:
diarrhoea
frequent passing of urine
headache
nervousness, restlessness
stomach upset
The LD50 for caffeine for oral administration in humans is 150mg/kg and 192mg/kg in rats.
