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My puppy vomited yellow after Nexgard/Heartgard. Is it meds or worms?

Updated On September 23rd, 2025

Pet's info: Dog | Beagle | Female | unspayed | 1 month and 26 days old | 6 lbs

Earlier today i gave my 8 week beagle pup nexgard and heartguard at the same day and then this evening i noticed a few roundworms in my one of my puppies bowel movement, and this evening she is having belly issues and vomitted a yellowish liquid almost a yellow bile this evening, its too late to contact a vet any suggestions would be helpful, could it be a reaction to both meds or the roundworms or something else entirely

1 Answer

Most Helpful Answer

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Answered By Laura Johnson VMD

Veterinarian

Published on September 8th, 2018

Hi, thanks for using Petco Pet Education Center, formerly Petcoach! Poor Lucy! I always recommend the first time giving nexgard and heartgard to separate them out by 2 days in case there is a reaction we know which drug it could be. Both have the potential to cause an upset stomach. Also having intestinal parasites can cause vomiting and diarrhea. The heatgard kills round worms so that could be why Lucy passed the worm after you gave the medication. Sadly both are possible causes for her upset stomach. Usually all quickly resolve. Just watch her closely for the next several hours. If she continues to vomit or won't eat this morning I would call your Vet when they open this morning and have her seen before they close for the weekend. Good luck!

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1Pet Parents found this answer helpful

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