Credelio for Dogs: Complete Dosage, Safety & Cost Guide
Everything you need to know about Credelio for dogs: dosage by weight, side effects, drug interactions, cost, and vet-recommended alternatives.
What Is Credelio for Dogs and What Does It Treat?
Credelio is a flavored, chewable oral tablet manufactured by Elanco Animal Health that contains the active ingredient lotilaner. It belongs to the isoxazoline class of parasiticides — the same drug family as Bravecto (fluralaner), NexGard (afoxolaner), and Simparica (sarolaner). Credelio was FDA-approved for veterinary use in January 2018 specifically for canine patients.
Credelio is indicated for the treatment and prevention of flea infestations (Ctenocephalides felis) and the treatment and control of four tick species in dogs and puppies 8 weeks of age and older, weighing at least 4.4 pounds (2 kg):
- Lone star tick (Amblyomma americanum)
- American dog tick (Dermacentor variabilis)
- Brown dog tick (Rhipicephalus sanguineus)
- Black-legged tick / deer tick (Ixodes scapularis)
Credelio kills adult fleas and is indicated for the treatment and prevention of flea infestations. It also treats and controls the tick species listed above for one full month. According to the FDA's approval documentation, Credelio begins killing fleas within 4 hours of administration and achieves greater than 99% flea efficacy within 12 hours.
How Credelio Works: Mechanism of Action
Lotilaner is an ectoparasiticide that acts as a GABA-gated chloride channel antagonist and also inhibits glutamate-gated chloride channels in the parasite's nervous system. When a flea or tick bites a Credelio-treated dog, it ingests lotilaner through the blood meal. The drug then blocks the parasite's ability to regulate chloride ion flow across neural membranes, causing uncontrolled neural activity, paralysis, and death of the parasite.
Because lotilaner targets invertebrate-specific receptor subtypes, it has a wide safety margin in mammals — canine GABA receptors have a structurally different binding site. However, this mechanism is the same reason isoxazolines carry a seizure warning for dogs with pre-existing neurological conditions (more on this below).
Credelio Dosage Guide by Dog Weight
Credelio is dosed at a minimum of 20 mg/kg (9.1 mg/lb) of lotilaner per pound of body weight, administered once monthly. Elanco manufactures Credelio in six pre-scored chewable tablet strengths to match specific weight ranges. Your veterinarian will select the appropriate tablet based on your dog's current weight.
| Tablet Strength | Dog Weight Range | Lotilaner per Tablet (mg) | Flea & Tick Prevention |
|---|---|---|---|
| 56.25 mg | 4.4 – 6.0 lb (2.0 – 2.7 kg) | 56.25 | 1 tablet monthly |
| 112.5 mg | 6.1 – 12.5 lb (2.8 – 5.7 kg) | 112.5 | 1 tablet monthly |
| 225 mg | 12.6 – 25.0 lb (5.8 – 11.3 kg) | 225 | 1 tablet monthly |
| 450 mg | 25.1 – 50.0 lb (11.4 – 22.7 kg) | 450 | 1 tablet monthly |
| 900 mg | 50.1 – 100.0 lb (22.8 – 45.4 kg) | 900 | 1 tablet monthly |
| 1350 mg | 100.1 – 150.0 lb (45.5 – 68.0 kg) | 1350 | 1 tablet monthly |
Important administration note: Credelio must be given with food or within 30 minutes of feeding. Lotilaner absorption is significantly reduced on an empty stomach, which can result in sub-therapeutic blood levels and reduced efficacy against parasites. This is a key difference from some other isoxazolines — Simparica (sarolaner), for example, can be given with or without food.
If your dog vomits within one hour of administration, contact your veterinarian. A replacement dose may be recommended to ensure adequate parasite protection.
Credelio Side Effects: What to Watch For
In field studies reviewed by the FDA, Credelio was well tolerated by the majority of canine patients. However, as with all isoxazoline-class drugs, there are both common and serious side effects to be aware of. The Merck Veterinary Manual notes that isoxazolines as a class carry an FDA warning regarding potential neurologic adverse events.
| Side Effect | Reported Frequency | Severity | Action Required |
|---|---|---|---|
| Vomiting | ~3.7% | Mild | Monitor; ensure given with food |
| Diarrhea | ~2.2% | Mild | Monitor; contact vet if persistent >48 hrs |
| Lethargy / decreased activity | ~1.1% | Mild–Moderate | Monitor; contact vet if >24 hrs |
| Decreased appetite | <1% | Mild | Monitor |
| Seizures / tremors / ataxia | Rare (post-approval reports) | SERIOUS | Emergency vet visit immediately |
| Severe allergic reaction (anaphylaxis) | Very rare | SERIOUS | Emergency vet visit immediately |
🚨 Seek Immediate Veterinary Care If Your Dog Experiences:
- Seizures or convulsions (even a single episode)
- Muscle tremors or uncontrolled shaking
- Ataxia (stumbling, loss of coordination, inability to stand)
- Facial swelling, hives, or difficulty breathing
- Persistent vomiting (more than 2 episodes in 24 hours)
- Complete refusal to eat for more than 48 hours
For suspected drug-related adverse events, you or your veterinarian can report to Elanco at 1-888-545-5973 or to the FDA at fda.gov/reportanimalae.
Contraindications: Dogs Who Should NOT Receive Credelio
While Credelio has a broad safety profile, certain dogs should not receive this medication or require careful veterinary risk-benefit analysis before use:
- Puppies under 8 weeks of age — safety has not been established in very young puppies
- Puppies weighing less than 4.4 lb (2 kg) — no appropriate tablet strength is available, and safety data is limited
- Dogs with a history of seizures or epilepsy — the FDA issued a class-wide warning in September 2018 that isoxazolines (including lotilaner) can cause neurologic adverse events including seizures, tremors, and ataxia in dogs with or without pre-existing seizure disorders. Your veterinarian may recommend an alternative drug class
- Dogs with known hypersensitivity to lotilaner or any inactive ingredients in the tablet
- Intact breeding dogs — the safe use of Credelio has not been evaluated in breeding, pregnant, or lactating dogs. Discuss alternatives with your vet if your dog is part of a breeding program
The seizure warning deserves particular emphasis. While post-marketing reports of seizures are classified as rare, the FDA determined the risk significant enough to mandate labeling changes across all isoxazoline products. If your dog has any history of seizures — even a single episode — your veterinarian will likely consider non-isoxazoline alternatives such as topical or collar-based preventives.
Drug Interactions and Monitoring Requirements
Credelio (lotilaner) is primarily metabolized by hepatic cytochrome P450 enzymes. While clinically significant drug interactions are uncommon in practice, several combinations warrant veterinary awareness:
| Concurrent Medication | Interaction Type | Risk Level | Veterinary Recommendation |
|---|---|---|---|
| Phenobarbital (seizure medication) | CYP450 induction may alter lotilaner metabolism | Moderate | Avoid combination — seizure history is a contraindication for isoxazolines |
| Potassium bromide | Same as above; also indicates seizure disorder | Moderate | Avoid combination |
| Ivermectin (high-dose, off-label) | Both cross blood-brain barrier; additive neurotoxicity risk in MDR1-mutant breeds | Moderate–High | Use with caution in herding breeds; MDR1 testing recommended |
| Other isoxazolines (Bravecto, NexGard, Simparica) | Duplicate therapy; increased adverse event risk | High | Never combine; choose one isoxazoline product only |
| NSAIDs (carprofen, meloxicam, deracoxib) | No known direct interaction | Low | Generally safe to co-administer |
| Heartworm preventives (ivermectin at preventive dose, milbemycin, moxidectin) | No clinically significant interaction at labeled doses | Low | Safe to co-administer; Credelio does NOT prevent heartworm |
Monitoring Schedule
Credelio does not require routine blood work or laboratory monitoring in healthy dogs. However, your veterinarian may recommend the following:
- Baseline weight check before starting to ensure correct tablet strength selection
- Re-weigh at annual wellness visits — weight changes may require a different tablet strength
- Neurological monitoring for the first 2–3 doses — observe your dog for 24 hours after each of the first few administrations for any tremors, ataxia, or unusual behavior
- Annual heartworm testing — Credelio does not prevent heartworm disease, so your dog still needs a separate heartworm preventive and annual antigen test
How Long Does My Dog Need to Be on Credelio?
Flea and tick prevention is generally a long-term, ongoing commitment rather than a short course of treatment. The duration depends on your geographic location, your dog's lifestyle, and your veterinarian's assessment of parasite risk:
- Year-round prevention (12 months) is recommended by the Companion Animal Parasite Council (CAPC) and most veterinary parasitologists for dogs in most of the United States. Fleas can survive indoors year-round, and ticks in many regions are active in all four seasons.
- Seasonal prevention (6–8 months) may be appropriate for dogs in northern climates with reliably cold winters (sustained temperatures below freezing) and strictly indoor lifestyles. However, even in cold regions, ticks like Ixodes scapularis (deer ticks) can remain active on warmer winter days.
- Treatment duration for active infestations: If your dog already has fleas, Credelio begins killing them within 4 hours. However, because flea life cycles span 3–6 weeks (egg → larva → pupa → adult), you should expect to administer Credelio for a minimum of 3 consecutive months to fully break the flea life cycle in your home and yard.
Never stop Credelio mid-month or skip doses without consulting your veterinarian. Gaps in coverage allow parasite populations to rebound quickly.
Credelio Cost and Generic Availability
As of 2026, Credelio does not have a generic equivalent available in the United States. Lotilaner is still under Elanco's patent protection, so only brand-name Credelio is available through licensed veterinary pharmacies and veterinary clinics.
| Tablet Strength / Weight Range | Cost per Dose (Clinic) | Cost per Dose (Online Pharmacy) | Annual Cost (12 months) |
|---|---|---|---|
| 56.25 mg (4.4–6 lb) | $18–$22 | $15–$19 | $180–$264 |
| 112.5 mg (6.1–12.5 lb) | $19–$24 | $16–$20 | $192–$288 |
| 225 mg (12.6–25 lb) | $21–$26 | $17–$22 | $204–$312 |
| 450 mg (25.1–50 lb) | $23–$29 | $19–$24 | $228–$348 |
| 900 mg (50.1–100 lb) | $27–$34 | $22–$28 | $264–$408 |
| 1350 mg (100.1–150 lb) | $32–$40 | $26–$33 | $312–$480 |
Cost-saving tips: Many veterinary clinics offer 6-month or 12-month multi-packs at a 10–15% discount compared to monthly single-dose purchases. Some online veterinary pharmacies (Chewy Pharmacy, Covetrus, VetRxDirect) offer auto-ship discounts when your veterinarian sends a prescription directly. Always verify that any online pharmacy requires a valid prescription — sites selling Credelio without one are operating illegally and may sell counterfeit product.
Missed Dose and Overdose: What to Do
If You Miss a Dose
If you forget to give Credelio on the scheduled date, administer the tablet as soon as you remember, with food. Then resume the monthly schedule based on this new administration date (i.e., the next dose is due 30 days from the late dose, not the original date). Your dog will have a gap in parasite protection during the missed period, so check your dog thoroughly for ticks and monitor for flea activity.
If the gap between doses exceeds 6 weeks, consult your veterinarian — they may recommend a bath with a fast-acting adulticide shampoo to clear any parasites that established during the coverage gap before restarting Credelio.
If an Overdose Occurs
In safety studies, lotilaner was administered to dogs at up to 5 times the maximum labeled dose (100 mg/kg) without serious adverse effects. However, this does not mean overdoses are harmless. If your dog accidentally consumes multiple tablets or a higher-strength tablet intended for a larger dog:
- Remove any remaining tablets from your dog's reach immediately
- Note the exact amount ingested — tablet strength, number of tablets, and time of ingestion
- Contact your veterinarian or an emergency veterinary clinic
- Call ASPCA Animal Poison Control at (888) 426-4435 (24/7, consultation fee applies) or Pet Poison Helpline at (855) 764-7661 for immediate guidance
- Monitor for neurologic signs — tremors, ataxia, seizures — especially within the first 6–12 hours
Do not attempt to induce vomiting unless specifically instructed to do so by a veterinary professional.
Alternatives to Credelio: Comparing Isoxazolines and Other Options
If Credelio isn't the right fit for your dog — due to cost, side effects, the food requirement, or seizure history — several alternatives exist. Your veterinarian will help you choose based on your dog's health profile and parasite risk.
| Product | Active Ingredient | Duration | Food Required? | Key Difference |
|---|---|---|---|---|
| Credelio | Lotilaner | 1 month | Yes | Fast flea kill (4 hrs); strong tick coverage |
| Bravecto | Fluralaner | 12 weeks (oral) | Yes (recommended) | Longest duration; fewer annual doses |
| NexGard | Afoxolaner | 1 month | No (with or without) | Beef-flavored; also approved for sarcoptic mange |
| Simparica | Sarolaner | 1 month | No | Covers fleas, ticks, and sarcoptic mange |
| Simparica Trio | Sarolaner + moxidectin + pyrantel | 1 month | No | Flea/tick + heartworm + intestinal parasites in one |
| Seresto collar | Imidacloprid + flumethrin | 8 months | N/A (topical collar) | Non-isoxazoline option; safe for seizure-prone dogs |
| K9 Advantix II | Imidacloprid + permethrin + pyriproxyfen | 1 month | N/A (topical) | Repels AND kills; toxic to cats in household |
Key consideration for multi-pet households: If you have cats, avoid permethrin-containing topicals like K9 Advantix II — permethrin is highly toxic to cats. Oral isoxazolines like Credelio pose no risk to cats in the household because the medication is internal to the dog.
Frequently Asked Questions About Credelio
Does Credelio protect against heartworms or intestinal parasites?
No. Credelio only targets external parasites — fleas and ticks. It does not prevent heartworm disease, roundworms, hookworms, whipworms, or tapeworms. Your dog will need a separate heartworm preventive (such as Heartgard Plus, Interceptor Plus, or Revolution Plus) and possibly a dewormer, depending on fecal test results. Ask your veterinarian about combination products like Simparica Trio if you want to consolidate flea/tick, heartworm, and intestinal parasite protection into a single monthly dose.
Can I use Credelio on my cat?
No. Credelio is formulated and FDA-approved exclusively for dogs. The safety and efficacy of lotilaner in cats has not been established. Elanco does manufacture a separate feline parasiticide, but Credelio itself must never be given to cats or any species other than dogs.
How quickly does Credelio start working after the first dose?
Credelio begins killing fleas within 4 hours of administration. In controlled studies, it achieved 99.4% flea kill within 12 hours and maintained greater than 99% efficacy for the full 35-day dosing interval. For ticks, kill rates vary by species but generally reach significant levels within 48 hours of the tick attaching and feeding.
Is Credelio safe for dogs with the MDR1 gene mutation?
The MDR1 (ABCB1) gene mutation, common in herding breeds like Australian Shepherds, Collies, and German Shepherds, affects the blood-brain barrier's ability to pump certain drugs out of the central nervous system. While lotilaner is not a known MDR1 substrate at labeled doses, the isoxazoline class does act on the nervous system. If your dog is MDR1-positive or untested, discuss this with your veterinarian. Washington State University's Veterinary Clinical Pharmacology Laboratory maintains a current list of drugs of concern for MDR1-mutant dogs.
My dog is a picky eater. What if they won't eat the Credelio tablet?
Credelio tablets are beef-flavored and chewable, and most dogs accept them readily. If your dog refuses the tablet, try hiding it in a small amount of a high-value food (peanut butter, cheese, or a pill pocket). The critical requirement is that Credelio is given with food — so even if you use a treat to disguise it, ensure your dog has eaten a meal within 30 minutes of administration. If your dog consistently refuses oral medications, a topical alternative like the Seresto collar may be a better fit.
Can I switch from Bravecto or NexGard to Credelio?
Yes, but timing matters. If switching from Bravecto (12-week product), wait until the current Bravecto dose is due for renewal, then start Credelio on that date. If switching from another monthly isoxazoline (NexGard, Simparica), administer the first Credelio dose on the date the next monthly dose would have been due. Do not overlap two isoxazoline products. Your veterinarian should guide the transition to avoid gaps in coverage.
Disclaimer: This article is for informational purposes only and does not replace professional veterinary advice. Always consult your veterinarian before starting, stopping, or changing any medication for your dog. Credelio requires a valid prescription from a licensed veterinarian.
Beth Carrasco
All our authors care for dogs every day — read more of their work on the authors page.
