Metronidazole

Indications

AYRADIA oral suspension is indicated for the treatment of Giardia duodenalis infection in dogs.

Dosage and Administration

Shake vigorously before use. AYRADIA oral suspension is administered orally at a dose of 25 mg/kg (11.3 mg/lb) of body weight, using the supplied syringe, twice daily for five consecutive days. Each line on the included dosing syringe represents 0.1 mL of oral suspension. For dogs weighing more than 15 kg (33 lb), the total dose volume will be divided over multiple syringe draws because the dosing syringe only holds up to 3 mL. Alternatively, a standard luer lock syringe that holds more than 3 mL can also be used. The flavored suspension can be administered directly into the mouth or in a small amount of food (see Instructions for Using the Dispensing System and Preparing a Dose of AYRADIA oral suspension on reverse side).

Contraindications

The use of this drug is contraindicated in animals with a history of a hypersensitivity to nitroimidazole compounds, including metronidazole.

Warnings

User Safety Warnings Keep out of reach of children. Not for use in humans. Metronidazole has been found to cause cancer in laboratory animals; however, there is inadequate evidence of carcinogenicity in humans. People with known sensitivity to metronidazole or other nitroimidazole derivatives should avoid contact with AYRADIA oral suspension. This product is not a dermal or eye irritant but is a skin sensitizer which can potentially cause allergic contact dermatitis. Wash hands after use. Avoid contact with skin. In case of skin contact, wash the affected area thoroughly. Persons who come in contact with the dog’s saliva during the first five minutes after administration should wash their hands. If the drug has been applied to dog food, the dog food should be kept away from children until after the dog has finished eating. Avoid accidental ingestion. In case of accidental ingestion, seek medical advice immediately. Animal Safety Warnings Federal law prohibits the extra-label use of this drug in food-producing animals. Keep AYRADIA oral suspension in a secure location out of reach of dogs, cats, and other animals to prevent accidental ingestion or overdose.

Precautions

Prescribing antimicrobial drugs in the absence of a proven or strongly suspected infection is unlikely to provide benefit to treated animals and may increase the risk of the development of drug resistant animal pathogens. Use with caution in dogs with hepatic dysfunction. Adverse neurologic effects have been associated with AYRADIA oral suspension use at high doses (see Target Animal Safety), but individual variation in sensitivity of dogs to the adverse neurologic effects of metronidazole has been reported. The safe use of this drug in dogs intended for breeding purposes and in pregnant or lactating bitches has not been evaluated.

Adverse Reactions

In a clinical field effectiveness and safety study, 120 dogs were treated with AYRADIA oral suspension and 60 dogs were treated with a vehicle control. The most frequently reported adverse reactions were diarrhea (6.7% treated, 5% vehicle) and vomiting (4.2% treated, 3.3% vehicle). One dog treated with AYRADIA oral suspension was reported to have hyperactivity while being treated. The safety of AYRADIA oral suspension was also evaluated in a masked, active-controlled, multi-site field study, to evaluate the effectiveness of AYRADIA oral suspension for the treatment of Giardia spp. in dogs. Enrollment included 180 client-owned dogs diagnosed with Giardia spp. infection; 91 dogs were treated with AYRADIA oral suspension at 25 mg/kg twice daily for 5 consecutive days and 89 were treated with an active control. The dogs were 7.8 weeks to 13.4 years old, various pure or mixed breeds, and intact or neutered male dogs or intact or spayed female dogs. The most frequently reported adverse reactions in dogs treated with AYRADIA oral suspension were vomiting (14.3%) and diarrhea (3.3%). Other less frequently reported (<1.2%) adverse reactions included hypersalivation, abdominal pain, polydipsia and polyuria, anorexia, otitis externa, and lethargy.

Description

AYRADIA™ (metronidazole oral suspension) for dogs contains metronidazole USP. Metronidazole is a nitroimidazole, in the drug class anti-infectives, with anti-bacterial and anti-protozoal activities. The product is a flavored oily suspension with brown visible particles. The chemical composition of metronidazole is 2-(2-methyl-5-nitroimidazol-1-yl) ethanol. The empirical formula of metronidazole is: C6H9N3O3. AYRADIA oral suspension contains 125 mg metronidazole/mL in a flavored, medium-chain triglyceride, liquid base.

Storage

Store below 86°F (30°C) in the upright position. Once opened, use within 6 months.

FDA adverse event reports

The FDA Center for Veterinary Medicine publishes the adverse event reports it receives through openFDA. The counts below are the reports naming metronidazole as an active ingredient for each species this label names, as returned on 2026-09-16, coded by the VeDDRA reaction term the reporter chose. Reactions are counted per report, so one report can appear under several terms.

These are counts, not rates. Reporting is voluntary, the number of animals treated is not known, and a widely used product accumulates reports for that reason alone. A report records that an event followed a dose; it does not establish that the product caused it. The counts say nothing about how one product compares with another.