Re: bad reaction to barefoot dewormer

Heart palpitations would be indicative of adrenal stress it would also indicate a possible magnesium deficiency or potassium deficiency. When the adrenals are pushed because of stress which could be die-off or a allergic type of reaction to some ingredient in the product, it will set off problems as you describe. You are probably getting some anxiety as well? Breathing issues would be the same (die off or allergic)

Wormwood is known for having some toxicity to it. You could switch to anti parasite formulas that do not contain Wormwood such as Amazon or Raintree's anti parasite formula or try the ayurvedic formula from Banyan's Botanicals.

If you suspect die-off then I would use charcoal (google Tom Harrelson's site for info) and drink alot of water.