L-lysine is itself an amino acid. L-lysine prevents the feline herpesvirus from accessing another amino acid, Arginine....which herpesvirus needs in order to replicate. When it can't replicate, and existing cells die off, the herpes outbreak has been quelled.
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I would not expect any cure from using this stuff. Reading about L lysine, on -line , the claims of benefits are enormous, it ‘s even sold for human ailments in so many forms and sold in so many forms to give to animals.. I would be so reluctant using this stuff.
The real question is since feline herpes is to my understand as common in cats as other ailment, for example worms. Please refer to a veterinary school for accurate information.