Medication Guide • Reviewed by Dr. Tiffany Delacruz, DVM
Frontline for Dogs
Frontline is a monthly topical flea and tick preventive applied between the shoulder blades. Frontline Plus also breaks the flea life cycle by killing eggs and larvae.
What Frontline is used for in dogs
- Monthly flea prevention
- Tick prevention
- Flea egg and larva control (Frontline Plus and Gold)
How it works
Fipronil distributes through the skin oil layer and kills fleas and ticks on contact. The newer Frontline Gold adds pyriproxyfen for faster kill.
Available formulations
Topical liquid by weight category
Frontline Plus
Frontline Gold
Side effects to know
Common side effects
- • Mild skin irritation at application site
These usually resolve on their own. If they persist past the first few doses, ask your vet.
Call your vet immediately if you see
- ⚠ Excessive grooming or distress at the site
- ⚠ Vomiting if the dog licks the application area
- ⚠ Severe skin reactions (rare)
Drug interactions
- • Generally minimal — topical application limits systemic exposure
When not to use
- • Puppies under 8 weeks
- • Sick or debilitated dogs (consult your vet first)
- • Never use dog formulations on cats — fipronil is OK for cats but the dog dosing is wrong
Monitoring during treatment
Apply to dry skin; don't bathe for 48 hours before or after application for best absorption.
Need a Frontline refill?
RexVet is the first 501(c)(3) non-profit online vet service in the U.S. Talk to a licensed veterinarian by video, get your dogs's Frontline prescription, and have it shipped through RexVetRx — all for $64.99 per visit.
Book a vet visit — $64.99Frontline for Dogs
Frequently asked questions
How long does Frontline last on dogs?
One application protects against fleas for 30 days and ticks for about 30 days. Reapply monthly for continuous coverage.
Can I bathe my dog after using Frontline?
Wait at least 48 hours after application. Frontline is water-resistant once absorbed, but premature bathing reduces effectiveness.
Frontline vs Simparica — which is better?
Both work. Simparica is an oral chewable with faster kill and includes more breeds in safety data. Frontline is topical and over-the-counter. Your vet can recommend based on your dog and lifestyle.
Can RexVet help me choose flea protection?
Yes — a quick RexVet video visit can recommend the right product based on your dog's age, weight, lifestyle, and any past reactions. We ship most products through RexVetRx.
Is Frontline safe for pregnant dogs?
Generally considered safe but always confirm with a vet before using any product on a pregnant or nursing dog.
Medical review by Dr. Tiffany Delacruz, DVM
Chief Executive Officer & Lead Veterinarian, RexVet. Licensed in Florida, New York, and Virginia.
Last fact-checked: 2026-05-19
Sources
This page is an educational reference and does not replace veterinary advice. Always consult a licensed veterinarian before starting, changing, or stopping medication for your pet.