The standard dose is one teaspoon of 3% hydrogen peroxide per five pounds of body weight, with an absolute maximum of three tablespoons (45 ml) for dogs weighing more than 45 pounds. This means a 20-pound dog gets four teaspoons, a 40-pound dog gets eight teaspoons, and anything above 45 pounds stays capped at three tablespoons regardless of size. Only use the common 3% household concentration, never food-grade or higher-strength formulas.
Dosing by Weight
The math is straightforward: divide your dog’s weight by five, and that’s how many teaspoons to give. Each teaspoon equals about 5 ml, so if you’re using an oral syringe instead of a spoon, multiply the number of teaspoons by five to get the volume in milliliters.
- 10-pound dog: 2 teaspoons (10 ml)
- 20-pound dog: 4 teaspoons (20 ml)
- 30-pound dog: 6 teaspoons (30 ml)
- 40-pound dog: 8 teaspoons (40 ml)
- 50+ pound dog: 3 tablespoons / 45 ml (maximum dose)
No matter how large your dog is, do not exceed three tablespoons total. A 100-pound Great Dane gets the same maximum as a 50-pound Husky.
How to Give It Safely
An oral syringe (without a needle) is the easiest and safest tool. A turkey baster also works. Draw up the correct amount, gently pull your dog’s lip out at the side of the mouth to create a small pocket, and slowly squirt the liquid onto the back of the tongue. Going slowly is important because squirting too fast raises the chance your dog inhales some of the liquid into the lungs.
Most dogs vomit within 10 to 15 minutes. If your dog hasn’t vomited after 15 minutes, you can give one more dose at the same amount. Do not give a third dose. If two rounds don’t work, the situation needs a veterinarian who can use a stronger prescription-only medication to induce vomiting.
Having your dog walk around gently after dosing can help stimulate the stomach and speed things along.
Only Use 3% Concentration
The brown bottle of hydrogen peroxide sold in most pharmacy aisles is 3%. That is the only concentration safe for this purpose. “Food-grade” hydrogen peroxide typically comes in concentrations of 10% to 35% and can cause severe chemical burns to your dog’s mouth, throat, esophagus, and stomach lining. Check the label before you use it. If you’re not sure of the concentration, don’t use it.
When You Should Not Induce Vomiting
Some situations become much worse if your dog vomits. Do not induce vomiting if your dog swallowed any of the following:
- Caustic or corrosive substances: Drain cleaner, oven cleaner, strong acids, or strong bases will burn the esophagus a second time on the way back up.
- Petroleum products: Gasoline, kerosene, motor oil, and similar hydrocarbons are easily inhaled into the lungs during vomiting, which can cause a dangerous type of pneumonia.
- Sharp objects: Bones, pins, glass, or anything with edges can tear tissue when forced back through the esophagus.
You should also skip hydrogen peroxide if your dog is already showing serious symptoms like seizures, extreme drowsiness, loss of coordination, or trouble breathing. A dog that’s seizing or barely conscious can’t protect its own airway, which means vomit can end up in the lungs. In all of these cases, go directly to an emergency vet.
Possible Side Effects
Even when used correctly, hydrogen peroxide is irritating to the digestive tract. Common side effects include continued nausea, diarrhea, and tiredness for several hours afterward. In some cases it can cause stomach ulcers, irritation to the esophagus, or a temporarily slower heart rate. These effects are usually mild and short-lived, but they’re worth knowing about so you’re not alarmed.
The more serious risk is aspiration, which happens when a dog breathes vomited material into the lungs. This can lead to pneumonia. Flat-faced breeds like Bulldogs, Pugs, French Bulldogs, Boston Terriers, and Pekingese have narrower airways that were historically thought to raise this risk, though recent veterinary research suggests the complication rate for these breeds may not be significantly higher than for other dogs when vomiting is induced in a clinical setting. Still, extra caution with short-nosed breeds is reasonable at home where you don’t have professional equipment standing by.
What to Do After Your Dog Vomits
Once your dog has vomited, check what came up. If you can identify the toxic substance in the vomit, that’s useful information for your vet. Keep a sample if possible.
Withhold food for a few hours to let the stomach settle, but offer small amounts of water so your dog stays hydrated. Watch for signs that something isn’t right: vomiting that continues for more than an hour or two after the peroxide dose, blood in the vomit, bloating, extreme lethargy, or difficulty breathing. Any of these warrant a vet visit.
Even if your dog vomits successfully and seems fine, calling your vet or an animal poison control hotline is still a good idea. Some toxins are absorbed quickly enough that vomiting alone doesn’t remove a dangerous amount, and your dog may still need further treatment.