About 30% of people with panic disorder use alcohol and 17% use other psychoactive drugs. Utilisation of recreational drugs or alcohol generally make symptoms worse (American Psychiatric Association: Practice guideline for the treatment of patients with panic disorder.)
Most stimulant drugs (caffeine, nicotine, cocaine) would be expected to worsen the condition, since they directly increase the symptoms of panic, such as heart rate. Cannabis commonly precipitates panic in panic patients.
People take recreational drugs to ‘heighten’ pleasurable sensations and feelings. However, the problem is that if we have been experiencing a low level of stress or anxiety (that we may not have even been aware of) then ‘recreational’ drugs can exaggerate THOSE feelings as well.
Then low level fight or flight symptoms can suddenly become very intense and this can lead to misinterpretation, catastrophisation and the formation of the cycle of fear.