When someone is under the influence of amphetamines, there are several signs and behaviors that are typically seen. One of the most common effects is increased energy and hyperactivity. People on amphetamines may feel restless and have a strong desire to move or keep themselves occupied. They may talk fast and be easily distracted, finding it difficult to concentrate on one task. This heightened energy can also lead to increased risk-taking behaviors, as individuals may feel more invincible and less cautious than usual. For example, someone may engage in reckless driving or unsafe sexual practices while under the influence. They may also have an exaggerated sense of self-confidence and may become argumentative or confrontational with others.

Another characteristic of amphetamine use is an increased heart rate and blood pressure. This can lead to a variety of physical symptoms such as a rapid pulse, sweating, and dilated pupils. Someone on amphetamines may also experience reduced appetite and experience weight loss over time. It is important to note that these physical symptoms can vary from person to person and may be dependent on the individual's tolerance and dosage. Additionally, the effects of amphetamines can last for several hours, meaning that a person may display these characteristics for an extended period of time.

In addition to the physical signs, amphetamine use can also have psychological effects on individuals. These drugs can cause feelings of euphoria and a sense of well-being, resulting in a heightened mood. However, as the effects wear off, individuals may experience irritability, mood swings, and even depression. This crash can be intense and lead to a cycle of repeated drug use in order to avoid the negative withdrawal symptoms. It is important to recognize that amphetamine use can have serious consequences on someone's physical and mental health, and that seeking help is crucial for their well-being.