According to Helpguide.org, people who experience anxiety undergo rapid heartbeat, difficulty breathing, feelings of dread or impending doom and difficulty concentrating. Anxiety can strike people at different times and for different reasons. Additional symptoms manifest as bowel irritation, sweating, insomnia, irritability and tense muscles. Symptoms often compound, can be difficult to control and increase a person's immediate sense of danger.
As Helpguide.org explains, many people who suffer from extreme anxiety complain that the symptoms feel similar to a heart attack. It is not uncommon for people with anxiety disorders to feel that they are dying. It is normal for people to experience anxious feelings at certain times during their lives, such as when asked to speak publicly or when preparing for an important academic exam. For some people, however, this feeling occurs much more frequently and is often prompted by reasons that seem to be out of their control. People who battle with anxiety disorders regularly complain that their symptoms arise without provocation. These symptoms arrest the ability to reason and manage a calm state of mind. Helpguide.org notes that anxiety is often linked to depression, and these two disorders can exacerbate one another if not treated by a professional.