A panic attack is a full activation of the fight-or-flight response in the absence of a threat. Everything that happens is the system working correctly; it has simply fired when there was nothing to run from.
It peaks within about ten minutes — that’s part of the clinical definition — and it can’t sustain itself, because the physiological state it involves is metabolically expensive and the body has counter-mechanisms that bring it down.
What each symptom is for
Racing heart. Pushing oxygenated blood to the large muscles so you can run. Not a heart problem; a heart doing exactly what adrenaline tells it to.
Breathlessness, or breathing too fast. Taking on oxygen for exertion. The uncomfortable irony is that over-breathing lowers carbon dioxide, which produces dizziness, tingling in the hands and face, and a sense of unreality — so the breathing intended to help creates several of the frightening symptoms.
Chest tightness. The chest wall muscles tensing. Almost always muscular rather than cardiac, though see the first time.
Dizziness and unreality. Blood redistributing away from the head toward the limbs, plus the carbon dioxide effect. Derealisation is frightening and isn’t a sign of losing your mind.
Nausea and the urgent need for a bathroom. Digestion shutting down and the body lightening its load for flight. Undignified and entirely functional.
Sweating. Pre-cooling for exertion. Tunnel vision. Attention narrowing to the threat. Shaking. Muscles primed and unused.
What it isn’t
You aren’t going to faint. Fainting requires a drop in blood pressure and panic raises it — the main exception is blood and needle phobia, which has its own reflex. You aren’t going to stop breathing; the brainstem doesn’t take instructions from panic. You aren’t going mad. And it doesn’t damage your heart.
The part that turns it into a disorder
One panic attack is unpleasant and unremarkable — a large proportion of people have one at some point. Panic disorder is what happens next: you start watching for the next one.
Attention turns inward, and inward attention finds things. A slightly fast heartbeat after stairs. A strange breath. Each detection triggers alarm, which produces the sensations, which confirms the alarm. That loop is the disorder, and it’s what treatment targets.
What to do during one
Not much, deliberately. Do not fight it — fighting adds arousal. Do not leave, if you can manage it, because leaving teaches that leaving was necessary. Slow the exhale, since over-breathing is producing a good deal of the discomfort. And let it peak, on the understanding that it can’t stay there.
The counterintuitive instruction that ends panic disorder is to stop trying to prevent attacks —and eventually to produce the sensations on purpose.