There are a number of symptoms that are commonly found in PD. The most important symptom is the onset of unexpected panic attacks. Some of the attacks come completely out of the blue and may even occur during sleep. Attacks may repeat when a person is in a similar situation or in specific places.

The attacks can be quite severe with rapid heart pounding, breathlessness, dizziness, fear of having a bowel movement, clammy hands and fear of loss of control. People may fear that they are about to collapse and die.

PD can lead to agoraphobia – the fear of public places – in order to avoid the circumstances or places that can lead to panic attacks. In very severe cases the avoidance may lead to the person becoming housebound and unable to go anywhere unaccompanied.

PD is also associated with at least four of the following symptoms:

• Restlessness or feeling "keyed up" or "on edge"
• Fatigue and being easily rundown
• Difficulty concentrating
• Irritability
• Muscle tension
• Sleep disturbance (difficulty falling or staying asleep, or unsatisfying sleep).