It’s a dangerous drug, that’s for sure.
‘High doses [of MA] may lead to aggressiveness, hostility and violent behaviour.
These effects vary from person to person, and are influenced by factors such as the person's weight, how much they have eaten, their general health, how much of the drug they have taken, and whether they have taken any other drugs.
Taking large quantities can intensify some of the effects. Heavy users may also experience effects such as:
- blurred vision
- tremors
- irregular breathing
- loss of coordination
- collapse.
The most serious effects of taking large quantities may include stroke, heart failure, seizures and excessively high body temperature.
Cardiac effects
Heavy methamphetamine use is associated with a range of chronic and acute cardiovascular problems including stroke, heart failure and seizures. Post-mortems of methamphetamine-related deaths of people in their 20s, 30s and 40s commonly reveal heart conditions more frequently associated with old age.’
Long term effects
Long term effects may include:
- agitation or aggression
- decreased motivation
- depression and anxiety
- poor concentration and memory
- psychotic symptoms such as paranoia and hallucinations
- disturbed sleep
- weight loss
- chest pains
METHAMPHETAMINE PSYCHOSIS
Methamphetamine use can induce psychosis with symptoms of paranoia and hallucinations, and can make people who have schizophrenia or other chronic psychotic symptoms worse.’
http://druginfo.sl.nsw.gov.au/drugs/a-to-z-of-drugs/ice-speed-other-methamphetamines