Methamphetamine increases heart rate which can cause users to feel short of breath. Some people may suddenly feel very frightened or paranoid which can trigger panic attacks. Click here for tips about how to help someone who is having a panic attack or experiencing other side effects. Other common symptoms include restlessness, trembling, dizziness, sweating, dry mouth, muscle aches, headaches, nausea or vomiting. These symptoms can leave users feeling agitated or nervous, particularly as the drug starts to wear off. If these symptoms persist for most days of the week, or for a few weeks or longer, it may be a sign that an anxiety disorder is present.