It might help if his adrenals are weak. Licorice root also stimulates the adrenals. Imo he needs to cut out all the fruit juice,fruit, alcohol,sugar and caffeine if he wants to feel better. If he can't eliminate the caffeine entirely, then cut down to perhaps one cup a day of coffee.

Some websites mention adrenal glandulars as possibly being helpful in panic attacks. They also mention that magnesium supplements are very important. Too much magnesium at one time will cause diarrhea though, so it should be given in relatively small amounts(perhaps 100-200 mg) several times a day. Magnesium malate would be good, especially if he has muscle ache.