Sympathomimetics are a class of drugs that mimic the effects of the sympathetic nervous system, which is responsible for the body's "fight or flight" response. These substances stimulate receptors that respond to norepinephrine and epinephrine, leading to increased heart rate, blood pressure, and energy levels. They are often used in medical settings to treat conditions like asthma, low blood pressure, and nasal congestion. Common examples of sympathomimetics include albuterol, which helps open airways in asthma patients, and pseudoephedrine, a decongestant found in many cold medications. While they can be effective, sympathomimetics may also have side effects, such as increased heart rate and anxiety, making it important to use them under medical supervision.