# TLDR Review: K9 Advantix II for Large Dogs

*Published: 2025-09-20 | Updated: 2025-09-20 | Source: https://shopsavvy.com/reviews-tldr/k9-advantix-ii-for-large-dogs*

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## Product: K9 Advantix II for Large Dogs
**Brand:** Bayer Animal Health

## Pros
- Effective against fleas, ticks, and mosquitoes without requiring pests to bite.
- Considered safer than oral medications as it can be washed off if an allergic reaction occurs.
- Seen as affordable and positively reviewed by some users.
- Can be applied in small amounts over multiple spots on the dog's back for better distribution.

## Cons
- Can cause adverse reactions such as tingling, redness, itching, and severe allergic responses.
- Not safe for cats; it is lethal to them.
- Ineffective in preventing tick and flea infestations for several users, despite previous success.
- Some dogs experienced discomfort, agitation, and even severe symptoms like seizures and skin irritation.
- Noticed a decline in product effectiveness, prompting some users to switch brands.

## Bottom Line

While Bayer K9 Advantix II offers broad-spectrum pest protection, it's crucial to monitor dogs for any adverse reactions, especially during the drying period after application. Some users report a decrease in effectiveness against fleas and ticks compared to previous batches. If your dog has a history of allergies or sensitivities, it might be wise to consult a vet before use or consider switching to an alternative product that's proven effective, such as a chewable treatment.

## Pros vs Cons at a Glance

| Pros | Cons |
|------|------|
| Effective against fleas, ticks, and mosquitoes without requiring pests to bite. | Can cause adverse reactions such as tingling, redness, itching, and severe allergic responses. |
| Considered safer than oral medications as it can be washed off if an allergic reaction occurs. | Not safe for cats; it is lethal to them. |
| Seen as affordable and positively reviewed by some users. | Ineffective in preventing tick and flea infestations for several users, despite previous success. |
| Can be applied in small amounts over multiple spots on the dog's back for better distribution. | Some dogs experienced discomfort, agitation, and even severe symptoms like seizures and skin irritation. |
|  | Noticed a decline in product effectiveness, prompting some users to switch brands. |

## Current Prices

| Retailer | Price | Availability |
|----------|-------|-------------|
| Petflow | $16.98  | Check |
| Yow Pet Supplies | $16.98  | Check |
| WalmartPetRx | $17.98  | Check |
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| Jefferspet.com | $31.99  | Check |
| PetSupermarket | $35.99  | Check |
| petsupplies.com | $39.99  | Check |
| VitalityMedical.com | $40.54  | Check |
| Tractor Supply | $51.99  | Check |
| Chewy.com | $55.69  | Check |
| Vitacost.com | $56.72  | Check |
| riograndetrade | $59.48  | Check |
| SuperShop | $64.99  | Check |
| Allivet Pet Pharmacy | $65.99  | Check |
| hollywoodfeed.com | $67.98  | Check |
| PetCareRx | $67.98  | Check |
| petocart.com | $68.67  | Check |
| Heartland Veterinary Supply and Pharmacy | $69.98  | Check |
| Instacart | $69.98  | Check |

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*About this review: We pulled together findings from professional and user reviews, and cross-referenced them with ShopSavvy's pricing data from thousands of retailers to give you the short version.*