• Following oral administration, peak methamphetamine concentrations are seen in 2.6-3.6 hours and the mean elimination half-life is 10.1 hours (range 6.4-15 hours).
• The amphetamine metabolite peaks at 12 hours.
• Following intravenous injection, the mean elimination half-life is slightly longer (12.2 hours).
• Overall effects typically last 4-8 hours; residual effects can last up to 12 hours.

As the effects of methamphetamine use begin to wear off, an individual may experience a range of effects.

• Methamphetamine can be swallowed, snorted, smoked or injected.
• Ice is usually smoked or injected.
• Depending on how methamphetamines are taken, the effects may be felt immediately (through injecting or smoking) or within 30 minutes (snorting) and approximately 20-30 minutes if swallowed.

A high dose of methamphetamines can cause an individual to overdose. 

This means that a person has used more methamphetamine than their body can cope with.  The risk of overdose increase if the strength or purity of the ice is not known.  Injecting ice increases the risk of overdose due to large amounts of the drug entering the blood stream and quickly travelling to the brain.

Apart from intensifying some of the effects already listed, high doses can also result in:

• Increased energy
• faster reaction times
• feeling more awake and alert
• reduced need for sleep
• a sense of euphoria and wellbeing
• increased attention and alertness
• increased talkativeness
• feelings of confidence and motivation
• increased libido

Base, crystal, ice, glass, crystal meth, shabu, ox blood, whizz, goey, louee

• dependence
• constipation
• menstrual irregularity; infertility in women
• loss of sex drive in men
• intense sadness
• cognitive impairment
• tetanus
• damage to heart, lungs, liver and brain
• damage to the nasal lining from repeated snorting
• vein damage from frequent injection
• skin, heart and lung infections from frequent injections
• damage to veins from injection of impurities and additives in heroin

• confusion
• constricted pupils
• lowered cough reflex
• reduced sexual urges
• drowsiness
• slurred and slow speech
• reduced coordination
• dry mouth
• decreased heart rate and blood pressure
• slow breathing rate
• nausea and vomiting
• reduced appetite

Repeated use of heroin can lead to neurobiological adaptation (dependence), specifically a reduction in numbers of endogenous opioid receptors. They may also develop a tolerance to heroin, which means they will need to use larger amounts to get the same effect.

Heroin withdrawal begins within 6-24 hours after last use, symptoms peak at 24-48 hours and subside within 5-10 days. Symptoms include: