^ Anxiety: management of anxiety (panic disorder, with or without agoraphobia, and generalised anxiety disorder) in adults in primary, secondary and community care. National Institute for Health and Clinical Excellence. Clinical Guideline 22. Issue date: April 2007 "Archived copy" (PDF). Archived from the original (PDF) on 24 August 2009. Retrieved 2009-07-21. ISBN 1-84629-400-2
Anxiety is distinguished from fear, which is an appropriate cognitive and emotional response to a perceived threat.[12] Anxiety is related to the specific behaviors of fight-or-flight responses, defensive behavior or escape. It occurs in situations only perceived as uncontrollable or unavoidable, but not realistically so.[13] David Barlow defines anxiety as "a future-oriented mood state in which one is not ready or prepared to attempt to cope with upcoming negative events,"[14] and that it is a distinction between future and present dangers which divides anxiety and fear. Another description of anxiety is agony, dread, terror, or even apprehension.[15] In positive psychology, anxiety is described as the mental state that results from a difficult challenge for which the subject has insufficient coping skills.[16]
Palpitations are uncomfortable sensations of the heart beating hard, rapidly, or irregularly. Some types of palpitations are benign, while others are more serious. Palpitations are diagnosed by taking the patient history and by performing an EKG or heart monitoring along with blood tests. An electrophysiology study may also be performed. Treatment of palpitations may include lifestyle changes, medication, ablation, or implantation of a pacemaker. The prognosis if palpitations depends on the underlying cause.
Many medical conditions can cause anxiety. This includes conditions that affect the ability to breathe, like COPD and asthma, and the difficulty in breathing that often occurs near death.[63][64][65] Conditions that cause abdominal pain or chest pain can cause anxiety and may in some cases be a somatization of anxiety;[66][67] the same is true for some sexual dysfunctions.[68][69] Conditions that affect the face or the skin can cause social anxiety especially among adolescents,[70] and developmental disabilities often lead to social anxiety for children as well.[71] Life-threatening conditions like cancer also cause anxiety.[72]
Some benefits of benzodiazepines are that they are effective in relieving anxiety and take effect more quickly than antidepressant medications often prescribed for anxiety. Some drawbacks of benzodiazepines are that people can build up a tolerance to them if they are taken over a long period of time and they may need higher and higher doses to get the same effect. Some people may even become dependent on them.
Some research suggests that people who have panic disorder might be very sensitive to sensory experiences (such as sunlight, smells and changes in the weather), but there's not enough evidence yet to say for sure. Also it's not clear whether having a high level of sensitivity to these sorts of things is something that might cause you to develop panic disorder, or whether it may be an effect of having it.

Panic attacks and panic disorder are not the same thing. Panic disorder involves recurrent panic attacks along with constant fears about having future attacks and, often, avoiding situations that may trigger or remind someone of previous attacks. Not all panic attacks are caused by panic disorder; other conditions may trigger a panic attack. They might include:
Hey I don’t know you but I’m going through the same exact thing I lost my son at 7 months just a hour after hearing his heartbeat strong and loud I have a four year old daughter and I’m trying to cope wit the reality and now scared that I might have health problems all this within two months it’s very very hard and I never had to deal with sadness and anxiety until now and it’s scarey
People will often experience panic attacks as a direct result of exposure to an object/situation that they have a phobia for. Panic attacks may also become situationally-bound when certain situations are associated with panic due to previously experiencing an attack in that particular situation. People may also have a cognitive or behavioral predisposition to having panic attacks in certain situations.

If you’re experiencing a lot of physical anxiety symptoms, you should start by getting a medical checkup. Your doctor can check to make sure that your anxiety isn’t caused by a medical condition, such as a thyroid problem, hypoglycemia, or asthma. Since certain drugs and supplements can cause anxiety, your doctor will also want to know about any prescriptions, over-the-counter medications, herbal remedies, and recreational drugs you’re taking.

If you are greatly afraid, however, such as being terrified that there is a burglar in your home that is about to harm you, the body produces a high degree stress response. We generally experience high degree stress responses as being anxiety attacks: where the changes are so profound they get our full attention. The greater the degree of anxiety and stress response, the more changes the body experiences.

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Separation anxiety disorder: Separation anxiety is often thought of as something that only children deal with; however, adults can also be diagnosed with separation anxiety disorder. People who have separation anxiety disorder have fears about being parted from people to whom they are attached. They often worry that some sort of harm or something untoward will happen to their attachment figures while they are separated. This fear leads them to avoid being separated from their attachment figures and to avoid being alone. People with separation anxiety may have nightmares about being separated from attachment figures or experience physical symptoms when separation occurs or is anticipated.