Crystal meth, also known as methamphetamine, is a highly addictive stimulant that is commonly smoked, injected, or snorted. It causes both short-term and long-term health effects. In the short-term, it can increase alertness but also cause irritability, paranoia, and increased heart rate. Long-term use is associated with anxiety, depression, severe weight loss, and potential brain and organ damage. The drug works by flooding the brain with dopamine, disrupting the brain's reward and pleasure systems.