Methamphetamine is a white, odorless, bitter-tasting crystalline powder that easily dissolves in water or alcohol.

Amphetamine is prescribed to treat some medical conditions, including:

obesity
ADHD
narcolepsy as (off-label)
Methamphetamine, a drug with a similar substance, is used illegally for its pleasurable effects. Misuse can be hazardous and even deadly.

Use and effects
Illegal forms of the drug can be smokedTrusted Source, snorted, injected, or ingested orally.

Smoking or injecting methamphetamine causes an immediate, intense “rush” or bliss that lasts for a few minutes.

Snorting does not produce the intense rush, but a euphoric high within 3 to 5 minutes of ingestion. The oral effects can be felt within 20 minutes.

Depending on how the drug is ingested, the effects can last for 6 to 24 hours.

Effects
People take methamphetamine for its pleasurableTrusted Source effects.
These include:

increased attention
higher levels of activity and talkativeness
decreased appetite
reduced fatigue
a feeling of power and self-control
a pleasurable sense of well-being or euphoria
There may also be:

faster breathing
a fast or irregular heartbeat
higher blood pressure
raised body temperature
How it works
The pleasurable effects of methamphetamine happen when the body releases very high levels of the neurotransmitter dopamine. This is the brain chemical involved in motivation, pleasure, and motor function.

As with many stimulants, methamphetamine is most often abused in a “binge and crash” pattern. Users try to maintain the high by taking more of the drug before the first dose wears off.

The drug acts on parts of the brain involved in reward, and this makes taking another dose tempting.

Some people binge for several days, avoiding food and sleep while continually using the drug until it is finished.

However, these high levels of dopamine are also thought to help make the drug more toxic to nerve terminals in the brain.

Methamphetamine is different from and more dangerous than other stimulants because a larger percentage of the drug remains unchanged in the body. This allows the drug to be present in the brain longer, extending the stimulant effects.
Doses and overdose
When amphetamine is prescribed legally, doses normally range from 2.5 to 10 mg daily, to a maximum 60 mg a day.

Since illegal drugs are not regulated, there is no way to know how much methamphetamine is in each illicit dose.

A high body temperature, heart attack, and seizures can occur with overdose. If not treated immediately, an overdose can result in organ failure and death.

Side effects
People use methamphetamine because they enjoy the effects. However, it can have some dangerous side effects.

These include:

increased distractibility
nausea
dry mouth and bad breath
dilated pupils
tremors
muscle twitching
memory loss
aggressive or violent behavior
mood disturbances
severe dental problems
weight loss
skin sores from intense itching
rapid or irregular heart rate
increased blood pressure
Long-term methamphetamine use can lead to:

feelings of aggressiveness and anxiety
confusion
insomnia
The following symptoms of methamphetamine psychosis are also possible:

paranoia
aggression
visual and auditory hallucinations
mood disturbances
delusions, such as the sensation of insects creeping on or under the skin
Paranoia can result in thoughts of homicide or suicide.