Tramadol for Dogs: Side Effects, and Why It May Not Do What You Think

If your vet prescribed tramadol for your arthritic dog and you cannot honestly tell whether it is doing anything, you are not being unobservant. There is a body of canine research that suggests you may be right.

This is an awkward article to write, because tramadol is prescribed constantly and in good faith. But the evidence is public, and a dog owner deserves to see it.

What Tramadol Is, and Why Vets Reach for It

Tramadol is a synthetic analgesic developed for people. In dogs it is used off-label, like gabapentin, which is normal in veterinary medicine but means there is no canine approval behind the label.

It is popular for understandable reasons. It is inexpensive, it has a long history of use, it does not carry the stomach and kidney cautions that NSAIDs do, and it can be given to dogs who cannot tolerate an anti-inflammatory. Vets prescribe it for post-surgical pain, for injuries, for cancer pain, and — most commonly — as an add-on for chronic arthritis.

It is worth being precise about how it works, because that is where the problem lives.

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Why Dogs Respond Differently

Tramadol on its own is a weak painkiller. It nudges serotonin and noradrenaline pathways, which contributes something, but the actual opioid effect comes from a metabolite the liver has to manufacture: O-desmethyltramadol, universally shortened to M1. M1 binds opioid receptors far more strongly than tramadol itself does.

In humans, that conversion happens readily enough to give a reliable effect. In dogs, it does not. The original canine pharmacokinetic work established the pathway, and a later study in 50 dogs recovering from knee surgery put it plainly: serum concentrations of M1 were low, and serum tramadol concentrations varied widely between individual dogs.

So two dogs on the same milligram-per-kilogram dose may end up with quite different amounts of the compound that actually relieves pain — and both may end up with very little.

The Trial That Changed the Conversation

In 2018, the Journal of the American Veterinary Medical Association published a randomized, blinded, placebo-controlled crossover trial designed to settle the question. Forty dogs with arthritis of the elbow or stifle, thirty-five of whom completed it. Each dog received, in random order, ten days of placebo, ten days of tramadol at 5 mg/kg every eight hours, and ten days of carprofen.

The researchers did not rely on impressions. They measured force-plate data — the actual weight the dog put through the sore limb — alongside owner-completed pain inventories.

Neither placebo nor tramadol produced any significant change from baseline in the force-plate measures or the pain scores. Carprofen did. The authors' conclusion was unambiguous: ten days of tramadol as administered "provided no clinical benefit for dogs with osteoarthritis of the elbow or stifle joint."

A veterinary trade publication covering the result ran it under the headline "Is tramadol the new placebo?" That is the tone of the professional conversation, and it has not been quietly reversed since.

What this does not mean

Three honest caveats, because overstating this would be its own kind of dishonesty.

• The trial tested one dose, one schedule, ten days, one condition. It does not prove tramadol is useless for acute post-surgical pain, for cancer pain, or in combination protocols where it may still contribute.
• Because M1 production varies so much between individuals, it remains possible that some dogs genuinely respond while the group average shows nothing.
• Your dog may be on it for a reason that has nothing to do with arthritis, and your vet may have a rationale you have not been told. Ask before concluding.

Side Effects of Tramadol in Dogs

Tramadol is generally well tolerated, which is part of why it stayed popular. The commonly reported effects:

• Sedation — the most frequent, especially at the start.
• Upset stomach — nausea, vomiting, reduced appetite, or constipation. Giving it with food usually helps.
• Dizziness or unsteadiness, sometimes described by owners as a dog that seems slightly drunk.
• Anxiety or restlessness — a paradoxical reaction in some dogs, the opposite of the expected calm.
• Tremors, which are less common and worth reporting.

The serious one is serotonin syndrome. Tramadol affects serotonin, so combining it with other serotonergic drugs — trazodone, fluoxetine, other SSRIs, certain behaviour medications — raises the risk. Signs include agitation, tremors, a high heart rate, vomiting, high temperature and, in severe cases, seizures. That is an emergency. Make sure your vet has a complete list of everything your dog takes, including supplements.

Do not stop it abruptly if your dog has been on it for an extended period. Tramadol is an opioid-type drug and withdrawal is possible; any reduction should be a taper your vet directs.

When Tramadol Should Be Avoided

• Dogs with a history of seizures or epilepsy — tramadol can lower the seizure threshold.
• Dogs on other serotonergic medication, unless your vet has weighed it deliberately.
• Dogs with significant liver or kidney disease, where clearance is impaired.
• Pregnant or nursing dogs, where safety is not established.
• Dogs on MAO inhibitors such as selegiline.
• Never a human tramadol formulation combined with acetaminophen — acetaminophen is dangerous to dogs. Check the label of anything you have at home before assuming it is the same drug.

Tramadol Is the One Drug the Hemp Research Flagged

Most "CBD drug interaction" lists for dogs are copied from human pharmacology and do not hold up when tested in dog tissue. Tramadol is the exception, and we would rather tell you that than leave it out.

A 2024 study in the Journal of Veterinary Pharmacology and Therapeutics tested CBD and CBDA against canine liver enzymes. Both inhibited the specific enzymes dogs use to process tramadol — CYP2B11, which handles one conversion step, and CYP2D15, which handles the other. Notably, the same study found CBD did not meaningfully inhibit CYP3A12, the canine counterpart to the human enzyme every generic warning list is built on.

That work was in vitro, and the authors called for live-dog confirmation. But it is the one interaction the canine evidence actually points at, so if your dog takes tramadol, name it to your vet specifically before adding hemp. We covered the whole picture drug by drug in our guide to CBD and your dog's medications.

If Tramadol Is Not Doing Much, What Then?

This is the productive version of the conversation, and it belongs with your vet rather than on the internet.

• An NSAID, if your dog can take one. In the trial above, carprofen was the arm that worked. Our write-up on Rimadyl and carprofen side effects covers the real risks honestly, including the liver question.
• Gabapentin, which addresses nerve-type pain rather than inflammation and has its own trade-offs — see our guide to gabapentin for dogs and its side effects.
• Weight and movement. Unglamorous, and the highest-value change most owners can make. Extra weight loads a sore joint every single step.
• The rest of the plan — traction at home, ramps, physical therapy, omega fatty acids, joint support.

On the hemp side, here is what our own research showed, stated at its actual strength. In a 90-day trial of 37 dogs with chronic joint discomfort, overseen by veterinary pain specialist Dr. Robin Downing with Colorado State University researchers, 23 dogs were taking gabapentin at enrollment; by the end, 10 had discontinued it and 11 had reduced their dose, every change made by that dog's own veterinarian. That trial measured gabapentin, not tramadol, and it was an open-label pilot without a control group. It is a signal worth knowing about, not a promise. The full write-up is on our clinical trials page.

Tramadol Dosage for Dogs by Weight

There is no FDA-approved tramadol product for dogs in the United States. When a US vet prescribes it, it is extra-label, as VCA's tramadol client sheet notes, and the tablet is usually the human 50 mg generic. The clearest published canine dose comes from a licensed veterinary product: the UK label for Tramadog 50 mg tablets for dogs gives 2–4 mg per kg every 8 hours, never closer than 6 hours apart, with a maximum of 16 mg/kg a day. That tablet splits into quarters (12.5 mg steps).

Calculated from the Tramadog SPC (UK Veterinary Medicines Directorate, revised July 2025). That label's own chart gives 1 × 50 mg at 12.5 kg and 2 × 50 mg at 25 kg at 4 mg/kg, and adds ¼ tablet per 3.12 kg above 25 kg. Your vet may prescribe differently; US vets are not bound to this label.

Your veterinarian sets the dose. This table shows how the published figure is calculated so you can check the arithmetic and ask better questions, not so you can dose without a prescription. Never give a human tablet to your dog without your vet telling you to. Two things are specific to this drug. First, a higher dose does not reliably fix a poor response. The label itself warns that some dogs are non-responders because they make little of the active metabolite. In the 40-dog placebo-controlled arthritis trial, tramadol at 5 mg/kg every 8 hours, already above that range, did no better than placebo. Second, the label rules it out with SSRIs, tricyclic antidepressants and MAO inhibitors, which includes trazodone and selegiline unless your vet has deliberately weighed the combination, and in dogs with epilepsy.

Is human tramadol the same as dog tramadol?

The molecule is the same, and US vets usually dispense the same 50 mg tablet. The danger is in the other products. Combination tablets with acetaminophen are toxic to dogs. Sugar-free liquid medicines are another trap: the Merck Veterinary Manual warns that sugar-free syrups and liquid formulations often contain xylitol, which is poisonous to dogs. Extended-release tablets should never be split. Only give a liquid or compounded tramadol your vet has confirmed is xylitol-free, and never use a family member's prescription.

Overdose signs and what to do

The label lists the signs of tramadol overdose as pinpoint pupils, vomiting, collapse, reduced consciousness up to coma, seizures and slowed or stopped breathing. Vets can partly reverse the breathing effects with naloxone. Tremors, agitation, a racing heart and high temperature in a dog also on trazodone or another serotonergic drug point toward serotonin syndrome. Either way, call your vet or the ASPCA Animal Poison Control Center on (888) 426-4435 (open 24 hours; a consultation fee may apply) now; do not wait to see whether it passes.

How to Give Tramadol Properly

1. Give it with food to reduce nausea, and keep the interval your vet set — commonly every eight to twelve hours.
2. Expect sedation early. It usually settles over the first several days.
3. Give it before activity, not after. It takes roughly one to two hours to reach peak effect.
4. Keep a simple log. Willingness to use stairs, gait on waking, how far into a walk before slowing. Impressions fade; notes do not — and this is exactly the evidence your vet needs to decide whether it is earning its place.
5. Tell your vet everything your dog takes, including behaviour medication and supplements, because of the serotonin risk.
6. Never stop it abruptly after long-term use, and never give a human combination product containing acetaminophen.

Questions Worth Asking Your Vet

• What is the tramadol specifically for in my dog — arthritis, nerve pain, something else?
• Have you seen the placebo-controlled arthritis trial, and does it change your thinking for my dog?
• If we are not sure it is helping, is there a structured way to find out?
• Is my dog a candidate for an NSAID instead, or alongside?
• What would a taper look like if we decided to come off it?

Frequently Asked Questions

Does tramadol actually work for dogs?
For chronic arthritis, the best available evidence says no. In a randomized, blinded, placebo-controlled crossover trial in 40 dogs, ten days of tramadol produced no significant change in force-plate measures or owner pain scores, and was indistinguishable from placebo, while carprofen in the same trial worked. It may still have a role in acute or post-surgical pain.

Why does tramadol work in people but not in dogs?
Tramadol itself is a weak painkiller; the opioid effect comes from a metabolite called M1 that the liver has to produce. Published canine studies repeatedly find low and highly variable M1 levels in dogs, which is the leading explanation for the difference.

What are the side effects of tramadol in dogs?
Sedation is the most common, along with nausea, vomiting, reduced appetite or constipation, and sometimes unsteadiness. Some dogs become restless rather than calm. The serious risk is serotonin syndrome when tramadol is combined with other serotonergic drugs such as trazodone or fluoxetine.

Can I stop my dog's tramadol?
Not on your own, and not abruptly after long-term use, because withdrawal is possible with an opioid-type drug. If you think it is not helping, bring your observations to your veterinarian and ask about a taper.

Can dogs take tramadol and CBD together?
This is the one combination the canine enzyme research specifically flags. A 2024 in vitro study found CBD and CBDA inhibited CYP2B11 and CYP2D15, the enzymes dogs use to process tramadol. Raise it with your veterinarian by name before adding hemp.

How long does tramadol take to work in dogs?
Roughly one to two hours to peak effect, which is why it is given before activity rather than after. It is typically dosed every eight to twelve hours.

Which dogs should not take tramadol?
Dogs with a seizure history, dogs on other serotonergic medication or MAO inhibitors such as selegiline, dogs with significant liver or kidney disease, and pregnant or nursing dogs. Never give a human tramadol product that also contains acetaminophen.

Is tramadol the same as an opioid?
It is an opioid-type drug, but a weak one in its parent form. Its opioid activity depends on conversion to M1, which is precisely the step dogs perform poorly and inconsistently.

How much tramadol can I give my dog?
Only what your veterinarian prescribes, because tramadol is extra-label for dogs in the US. The published veterinary label figure (UK Tramadog) is 2 to 4 mg per kg every 8 hours, no closer than 6 hours apart, up to 16 mg/kg a day. For a 40 lb (18 kg) dog that is about 36 to 73 mg per dose.

Is 50 mg of tramadol a lot for a dog?
It depends on weight. On the veterinary label range of 2 to 4 mg/kg, one 50 mg tablet is the top-of-range dose for a dog of about 12.5 kg (27.6 lb) and the bottom-of-range dose for a dog of about 25 kg (55 lb). For a small dog it can be too much; ask your vet before splitting or adjusting.

How much tramadol for a 100 lb dog?
A 100 lb dog weighs about 45.4 kg. At 2 to 4 mg/kg that is about 91 to 181 mg per dose, with a label maximum of about 726 mg in a day. Higher doses do not fix a poor response, because some dogs make little of the active metabolite, so talk to your vet if it is not helping.

Is tramadol for humans the same as tramadol for dogs?
The drug is the same, and US vets usually dispense the human 50 mg tablet. But human combination tablets with acetaminophen are toxic to dogs, extended-release tablets must not be split, and sugar-free liquids may contain xylitol. Only give a product your vet has prescribed for your dog.

Which is better for dog pain, tramadol or gabapentin?
Neither is the strongest-evidence choice for arthritis. In a 40-dog placebo-controlled trial, tramadol did no better than placebo while carprofen worked. Tramadol is labeled for acute and chronic mild pain and is often used short-term after surgery. Which fits your dog is your vet's call; our gabapentin and carprofen articles cover the evidence for each.

How We Sourced This Article

• Budsberg SC, Torres BT, Kleinhenz SN, et al. Lack of effectiveness of tramadol hydrochloride for the treatment of pain and joint dysfunction in dogs with chronic osteoarthritis. J Am Vet Med Assoc. 2018;252:427–432. PubMed. The placebo-controlled trial and the quoted conclusion.
• KuKanich B, Papich MG. Pharmacokinetics of tramadol and the metabolite O-desmethyltramadol in dogs. J Vet Pharmacol Ther. 2004;27:239–246. PubMed. Source for the canine metabolic pathway and M1.
• Benitez ME, Roush JK, McMurphy R, et al. Pharmacokinetics of hydrocodone and tramadol administered for control of postoperative pain in dogs following tibial plateau leveling osteotomy. Am J Vet Res. 2015;76:763–770. PubMed. Source for low and widely variable M1 concentrations in 50 client-owned dogs.
• Court MH, et al. Cannabidiol and cannabidiolic acid: Preliminary in vitro evaluation of metabolism and drug–drug interactions involving canine cytochrome P-450, UDP-glucuronosyltransferase, and P-glycoprotein. J Vet Pharmacol Ther. 2024;47:1–13. PubMed. Source for the CYP2B11 and CYP2D15 inhibition, and for CYP3A12 not being meaningfully inhibited.
• American Kennel Club — Tramadol for Dogs. Owner-facing overview of uses and reported side effects.
• Kogan L, Hellyer P, Downing R. The Use of Cannabidiol-Rich Hemp Oil Extract to Treat Canine Osteoarthritis-Related Pain: A Pilot Study. J Am Holist Vet Med Assoc. 2020;58:35–45. DOI 10.56641/UPRM3253. Our disclosure: HempMy Pet supplied the hemp extract and reimbursed clinic costs; per the journal we had no input into study design or interpretation.

If you find something here that conflicts with your veterinarian, email us at support@hempmypet.com and we will correct it.

These statements have not been evaluated by the Food and Drug Administration. Our products are not intended to diagnose, treat, cure, or prevent any disease. This article is educational and is not veterinary advice. Tramadol is a prescription medication — never start, stop, or change your dog's dose without your veterinarian.