
pan·ic at·tack
Noun: A sudden feeling of acute and disabling anxiety.
Ciel can suffer some intense panic attacks if he’s so closely reminded of a part of his more traumatic past. The symptoms include: Vomiting trouble breathing, blurred vision, growing weak/tired, accelerating heartbeat, and chest pains. The worse the panic attack, the worse his overall reaction afterward will be. After an attack, he may act on instinct to remove or get away from whatever it is that caused it. He considers this a major weakness, but there’s nothing he can do about it.
Under the cut is an example of him having a panic attack and then acting on his desire to get rid of the cause. It’s an excerpt from the manga, chapter 34.