Happins is powful fleand tk prection from nexgard. nexgard kills fleas and ticks all month long. and it comes in an easy-to-give tasty chew. and that makes dogs and owners happy. no wonder vets love it too. reported side effects include vomiting, itching, diarrhea, lethargy and lack of appetite. see your vet for more information on flea and tick protection you and your dog will love. nexgard. the vet s #1 choice. proven to protect street skaters and freestylers. stops up to 97% uv. lasts through heat. through sweat. coppertone. proven to protect.