Canker Sores Showdown: Tested Oils vs. Serums for Mouth Relief... (40) When we first stumbled upon the Canker Sores Treatment serum, we were skeptical but desperate for relief. The packaging promised "effective essential oil serum for canker sore relief," and honestly, we were intrigued. The 15 mL bottle felt compact and convenient, perfect for slipping into our bags. After applying it directly to a stubborn blister, we noticed a subtle tingling sensation followed by gradual healing. Unlike some oils that felt harsh, this serum was strangely soothing, leaving our gums feeling less inflamed within hours. True to its claim, we found it genuinely helpful for mouth ulcers—and we appreciated that it didn’t numb our mouths painfully. If we were to recommend a quick fix for painful blisters, this serum would be high on our list.