Fenbendazole 444 mg is a commonly used deworming medication for dogs, effective against intestinal parasites like roundworms, hookworms, and whipworms. It is generally considered safe and well-tolerated, but some pet owners notice changes in their dog’s behavior during treatment and wonder if the medication can cause sleepiness or reduced activity.

This temporary change is usually due to the body’s response to the dying parasites rather than the medication itself. As the worms are eliminated, the dog’s digestive system and immune response may cause mild discomfort or fatigue. Additionally, dogs with heavy parasite infections are often already low on energy, so they may seem more tired until their body begins to recover.

On the positive side, once the parasites are fully cleared, many dogs actually show increased energy, improved appetite, and better overall health. This is because their bodies can absorb nutrients more effectively without parasites interfering.