Taking even small amounts of methamphetamine can result in many of the same physical effects as those of other stimulants, such as cocaine or amphetamines. These include increased wakefulness, increased physical activity, decreased appetite, increased respiration, rapid heart rate, irregular heartbeat, increased blood pressure, and increased body temperature. Long-term methamphetamine use has many negative consequences for physical health, including extreme weight loss, severe dental problems (“meth mouth”), and skin sores caused by scratching.

Methamphetamine use also raises the risk of contracting infectious diseases like HIV and hepatitis B and C. These can be contracted both by sharing contaminated drug injection equipment and through unsafe sex. Regardless of how it is taken, methamphetamine alters judgment and inhibition and can lead people to engage in these and other types of risky behavior.

Methamphetamine use may also worsen the progression of HIV/AIDS and its consequences. Studies indicate that HIV causes more injury to neurons and greater cognitive impairment in individuals who are HIV-positive and use methamphetamine than it does in HIV-positive people who do not use the drug.