How long does it take for a dog to get rid of roundworms?

Finding roundworms in your dog’s stool or noticing them vomiting small, white worms is a common scare for owners—especially with puppies, who often pick up the parasites from their moms. You might first spot the signs during potty time, when tiny, spaghetti-like worms show up in the grass, or when your pup starts eating more but still loses weight. The question then becomes: how long until these worms are gone for good?

The timeline depends on treatment, but first, you need to follow local rules—many places require vet-prescribed dewormers for roundworms, not over-the-counter options. For example, in parts of Australia or France, using unapproved dewormers can lead to fines, since ineffective treatment lets roundworms spread (they can even infect humans). A vet will first test your dog’s stool to confirm roundworms, then give a dewormer that targets adult worms. Most dogs pass dead worms within 24 to 48 hours, but that doesn’t mean they’re fully clear yet.

Puppies usually need a second deworming 2 to 3 weeks after the first. That’s because roundworm eggs can linger in their intestines and hatch into larvae, which the first dose might not kill. You’ll probably notice your puppy has more energy once the second treatment kicks in—less lethargy during playtime and a steadier appetite. Adult dogs might only need one treatment if it’s their first case, but vets often suggest a follow-up stool test 4 to 6 weeks later to make sure no eggs are left. This step is key; skipping it could mean the worms come back.

Preventing reinfection matters just as much as the treatment itself. Roundworm eggs stick to shoes, dog beds, and even your clothes, so wiping your dog’s paws after walks (especially in parks or grassy areas) helps. Washing their bed in hot water every week kills any eggs, and picking up their poop right away stops eggs from spreading to other dogs or kids. Many regions have laws about cleaning up dog waste in public spaces—this isn’t just about politeness; it’s a way to stop parasites like roundworms from thriving in communities.

Getting rid of roundworms takes patience, but sticking to the vet’s plan ensures it’s done right. You’ll know your dog is clear when their stool tests come back negative, and they’re back to their usual self—chasing toys, eating well, and no more signs of worms. Remember, following local pet laws (like using vet dewormers and cleaning up waste) isn’t just a rule; it protects your dog, your family, and other pets. With the right steps, those pesky roundworms will be a thing of the past, and your pup can go back to enjoying their days without discomfort.