Parasiticides are the single biggest source of vet practice mark-up flagged by the CMA. Every UK practice stocks them, dispenses them at standard intervals, and applies a substantial dispensing margin to every dose. The CMA's 2026 Final Report singled them out by name.
For a typical medium dog on monthly flea/tick + monthly all-in-one wormer + tick collar, the annual cost at a vet practice runs to £350-£500. The same products from a VMD-approved online pharmacy come to £150-£250. The CMA's own number for typical owner overspend is £200 a year — that figure is mostly parasiticides.
Notable savings include generic spot-ons (Moxiclear instead of branded Advocate at roughly half the price), monthly chewables (Credelio, Simparica, NexGard all 35-50% cheaper online) and 8-month tick collars (Seresto at around £28-£32 online versus £40-£55 in clinic).
Because most parasiticides are sold without a written prescription, you do not even need to navigate the CMA's prescription rules. Just buy the same product from the cheaper pharmacy.