Should I deworm my puppy before vaccination?
Updated By PetymFacts checked against official sources on
Quick answer
In practice, yes, because deworming starts first. Parasite guidelines start puppy deworming at 2 weeks of age and repeat it every 2 weeks, while WSAVA starts core vaccines at 6 to 8 weeks. So a puppy on schedule has been dewormed at least twice before its first vaccine. No guideline we read sets a fixed gap between the two.
Both are part of one puppy plan that your vet sets. If your puppy has missed deworming, or is thin, pot-bellied or has diarrhoea, tell the vet at the vaccine visit: vaccines are meant for healthy animals, and the vet decides whether to vaccinate that day.
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How do deworming and vaccines fit together in the first months?
This is how the guidelines line up. Your vet adjusts it for your puppy, and for a puppy that came from the street or a shop with no records.
2 weeks
First deworming, with the mother treated at the same time. TroCCAP, CAPC and the Merck Veterinary Manual all start here; ESCCAP says from 14 days. Tropical Council for Companion Animal Parasites
4 and 6 weeks
Deworming repeated every 2 weeks, to stop worms caught before birth and from milk from becoming established. Tropical Council for Companion Animal Parasites
6 to 8 weeks
First core vaccine against distemper, adenovirus and parvovirus (the DHPPi on many Indian cards), as WSAVA recommends. WSAVAstudy
8 weeks
Last of the fortnightly dewormings in TroCCAP's tropical guideline; monthly after that. Tropical Council for Companion Animal Parasites
Every 2 to 4 weeks
Core vaccines repeated until the puppy is 16 weeks or older, WSAVA says. WSAVAstudy
Monthly to about 6 months
Deworming continues monthly, in Merck's and TroCCAP's advice; CAPC and ESCCAP suggest it where the risk stays high. Merck Veterinary Manual
26 weeks or later
WSAVA advises a core revaccination at or after 26 weeks for the few puppies whose earlier doses were blocked by their mother's antibodies. WSAVAstudy
Do the guidelines say how many days to leave between them?
No. We found no fixed gap in any of the primary guidelines.
You may be told that a puppy must be dewormed a set number of days before each vaccine. We read WSAVA's 2024 vaccination guidelines, the TroCCAP and ESCCAP parasite guidelines, CAPC's guidelines and the Merck Veterinary Manual, and none of them sets a rule on the order or a gap between the two. WSAVA treats vaccination as one part of a wider health plan that also covers detecting, treating and preventing internal and external parasites.
Merck's chapter on giving vaccines names one thing that blocks a young animal's response to vaccines: the antibodies it got from its mother. It does not mention worms. WSAVA says the same about the main cause of early vaccine failure, and that is why it recommends repeated doses ending at 16 weeks or older. So if your vet's clinic has a habit of deworming a few days before a vaccine visit, that is the clinic's practice, and a sensible way to keep both on track, not a rule from the guidelines.
What if my puppy has not been dewormed yet?
If Your puppy is bright, eating and growing, but you have no deworming record
Tell the vet at the first visit. The vet can start the deworming schedule and the vaccine schedule together and decide the order. WSAVAstudy
If Your puppy is thin, pot-bellied, has a dull coat or has passed worms
These are signs of a heavy roundworm burden, Merck says. The vet may treat the worms and examine the puppy before deciding on vaccines. Merck Veterinary Manual
If Your puppy is pale, weak or has black or bloody diarrhoea
See a vet today. Hookworm anaemia can kill young puppies, and bloody diarrhoea in a puppy can also be parvovirus. Companion Animal Parasite Council (CAPC)
If Your puppy is unwell for any reason
WSAVA advises against giving certain modified-live vaccines to sick pets that live in ordinary homes. Your vet decides whether to vaccinate that day or wait. WSAVAstudy
Why does deworming matter so much for young puppies?
Puppies are usually born with roundworms. Larvae resting in the mother wake during pregnancy and cross into the puppies before birth, and more come through her milk, TroCCAP says. Merck lists poor growth, loss of condition, a dull coat and a pot belly as the first signs. In hot, humid places, hookworms add the risk of anaemia: TroCCAP warns of bloody diarrhoea and death, sometimes from 10 days of age.
There is a family reason too. TroCCAP says children are most at risk from roundworm eggs in soil, and CDC says the infection can damage the eye. A puppy that is dewormed on time sheds fewer eggs onto your floor, your balcony and your society's lawns.
What should I bring and ask at the puppy's vaccine visit?
- Any vaccination card and deworming dates from the breeder, shelter or rescuer. Tropical Council for Companion Animal Parasites
- Notes on appetite, poo and energy over the last few days, and a photo of any worms seen. Merck Veterinary Manual
- Ask: when is the next deworming, and should it be on a different day from the vaccine? (Petym's suggested question.)
- Ask about a poo test: CAPC suggests at least 4 in the first year of life. Companion Animal Parasite Council (CAPC)
- Ask where your puppy can go before its course ends. WSAVA advises controlled socialisation, contact only with healthy puppies and fully vaccinated adult dogs, and avoiding possibly contaminated places outside the home. WSAVAstudy
- Write both schedules on the card, or in Petym's puppy vaccination schedule tool, so neither date slips.
Going away soon? Tell us your dates.
A checked local sitter feeds, walks and keeps your pet company at home, follows your care sheet to the letter and sends a photo every day. Petym is opening city by city: send your dates and we will tell you when a sitter can take them.
- Meet your sitter first, free
- PAN-checked, first-aid trained
- A photo every day
- Pay through Petym, never cash
Questions owners ask
Can a puppy be dewormed and vaccinated on the same day?
- None of the guidelines we read forbids it or requires a gap, so it is your vet's call. What matters most is that both schedules start on time: deworming from 2 weeks of age and core vaccines from 6 to 8 weeks.
Do worms stop a vaccine from working?
- The guidelines we read do not say so. WSAVA and the Merck Veterinary Manual name the mother's antibodies as the main thing that blocks early vaccines, which is why puppies get repeated doses until 16 weeks or older. Vaccines are meant for healthy animals, so a puppy made ill by worms should see the vet first.
My puppy was dewormed yesterday and has a vaccine today. Is that all right?
- Tell the vet at the visit, with the product name and date. No guideline we found sets a minimum gap, and the vet will examine the puppy and decide. Mention any vomiting, diarrhoea or loss of appetite since the deworming.
How often should my puppy be dewormed after vaccination starts?
- TroCCAP, written for the tropics, says every 2 weeks until 8 weeks of age, then monthly. Merck says monthly until about 6 months. After that your vet sets an adult schedule based on lifestyle; see Petym's answer on how often to deworm a dog.
Do the puppy vaccines protect against worms?
- No. The core puppy vaccines WSAVA lists protect against viruses: distemper, adenovirus and parvovirus, with rabies given separately. Worms are controlled by deworming on a repeating schedule, plus picking up poo and flea control. Both are needed, and your vet plans them together.
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Sources
Each source was opened and read on the date shown. How Petym checks its sources
- Merck Veterinary Manual: Administration of vaccines in animals (opens in a new tab)
- Tropical Council for Companion Animal Parasites: Canine guidelines: roundworms (opens in a new tab)
- Tropical Council for Companion Animal Parasites: Canine guidelines: hookworms (opens in a new tab)
- European Scientific Counsel Companion Animal Parasites (ESCCAP): GL1: worm control in dogs and cats (7th edition, June 2025) (opens in a new tab)
- Companion Animal Parasite Council (CAPC): General guidelines for dogs and cats (last updated 24 April 2025) (opens in a new tab)
- Companion Animal Parasite Council (CAPC): Hookworm guidelines for dogs and cats (last updated 28 February 2025) (opens in a new tab)
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- Merck Veterinary Manual: Gastrointestinal parasites of dogs (dog owners; last updated May 2026) (opens in a new tab)
- US Centers for Disease Control and Prevention: About toxocariasis (opens in a new tab)
- WSAVA: 2024 guidelines for the vaccination of dogs and cats (WSAVA Vaccination Guidelines Group, Journal of Small Animal Practice) (opens in a new tab)