Side effects, when they happen, are usually digestive: softer stool, gassiness, or a brief change in appetite. These issues are often about dose size, sudden introduction, or sensitivity to other ingredients in the product rather than collagen alone. Starting low and increasing gradually can help you see what your dog tolerates comfortably—especially if you’re also changing foods or adding other toppers.
If you notice vomiting, persistent diarrhea, facial swelling, hives, or intense itching, stop the supplement and contact your veterinarian promptly. Toxicity findings in other species don’t automatically translate to dogs, but they’re a reminder to treat any concentrated ingredient with respect (Gomes SA, 1991). The best results come from steady use that never compromises comfort.