Less serious side effects include: 1  Loss of appetite. 2  Weight loss. 3  Nausea. 4  Vomiting. 5  Diarrhea. 6  Frequent urination. 7  Muscle cramps, painful and swollen joints. 8  Excessive tiredness. 9  Difficulty falling asleep. 10  Headache, nervousness, dizziness. 11  Depression, mood swings. 12  Vivid dreams.
Nausea can occur in dogs for many reasons, particularly when the digestive tract and nervous systems are out of balance. Stress can certainly play a role in nausea.
Cephalexin for Dogs. Veterinarians often prescribe cephalexin to dogs with bacterial infections including skin, bone, urinary tract, respiratory, and other infections. The drug can be given with food and is usually well-tolerated by dogs, but some may have side effects including nausea or vomiting.