Grand Canyon hiker bitten by snake had an allergic reaction to the antivenom that almost killed her because it is made from horses

A woman who had been hiking in the Grand Canyon and then bitten by a snake was almost killed by the antivenom made from horses, which she was severely allergic to.

Alyson Redmond and her father, along with eight others, had been spending six days backpacking the North Rim of the Grand Canyon. 

She was bitten as she and the group rested at the Thunder River, following a seven-mile hike. 

'I never felt something like this,' Redmond explained to AZ Family. 'I definitely felt something go in and out, so we first thought it might have been a stinger that went in and out, a bee sting or a wasp.' 

Alyson Redmond was bitten by a snake as she rested at Thunder River while enjoying six days of backpacking the North Rim of the Grand Canyon

Redmond went to sleep that night and woke to loads of swelling, forcing her to cut her first trip to the Grand Canyon short as she was flown out. 

Paramedics took her to Flagstaff Medical Center, believing she had been bitten by a snake. But things quickly took a turn for the worse when she was given a higher dose of antivenom. 

She said: 'Within the first ten minutes I actually had the reaction. I looked at the nurse and said "something is wrong" and cause they're wearing the mask you could see her eyes get huge.'

Paramedics took her to Flagstaff Medical Center, where she was given a higher dose of antivenom

 But the antivenom caused Redmond to go into anaphylactic shock as it was made from the antibodies of horses, which she was allergic to

Redmond went into anaphylactic shock and had to be rushed to Phoenix. She recovered after three days and was given a different antivenom, one made from sheep. 

'I can be around horses and not go into shock,' said Redmond. 'It could be a happy coincidence.'

Antivenoms are made from the antibodies of animals, or in Redmonds case, made from a horse - which she is allergic to.  

Redmond recovered after three days and was given a different anti-venom

'To get really sick on this is almost unheard of,' said Dr. Frank LoVecchio, a toxicologist. 

The rarity in the sickness is so because most hospital-use antivenoms usually don't have traces of the animal they came from.  

'In an ideal world, the amount of animal proteins you get is extremely small almost negligible,' added Dr. LoVecchio. 'But when you have bad allergies or potential allergic reactions then these things can happen.'