Anti-aging supplements for dogs side effects are typically mild when formulas are well-designed, but “mild” still matters in older dogs. The most common issues are gastrointestinal: softer stool, gas, or brief appetite changes. These effects can be more noticeable in seniors because nutrient digestibility can shift with age and diet moisture, changing how the gut handles new inputs (Kim, 2021).
Stop and reassess if you see persistent vomiting, marked lethargy, hives, facial swelling, or any sudden behavior change. Those signs deserve a veterinary call, regardless of whether the supplement seems “natural.” If your dog has pancreatitis history, inflammatory bowel disease, or food sensitivities, introduce any new product with extra caution and a shorter trial window (Laflamme, 2005).