Short-term effects

    Loss of appetite
    Increased heart rate, blood pressure, body temperature
    Dilation of pupils
    Disturbed sleep patterns
    Nausea
    Bizarre, erratic, sometimes violent behavior
    Hallucinations, hyperexcitability, irritability
    Panic and psychosis
    Convulsions, seizures and death from high doses

Long-term effects

    Permanent damage to blood vessels of heart and brain, high blood pressure leading to heart attacks, strokes and death
    Liver, kidney and lung damage
    Destruction of tissues in nose if sniffed
    Respiratory (breathing) problems if smoked
    Infectious diseases and abscesses if injected
    Malnutrition, weight loss
    Disorientation, apathy, confused exhaustion
    Strong psychological dependence
    Psychosis
    Depression