Vaseline petroleum jelly is a go-to recommendation for stubborn, chapped lips. Plain petroleum jelly is an occlusive that helps reduce water loss and protect the lips while they heal.But there is another reason Vaseline can be especially useful when chapped lips just won't go away. Contact dermatitis can be a hidden cause of persistent lip irritation, and some lip balms and ointments contain additional ingredients that can trigger an allergic or irritant reaction.Plain petroleum jelly has a very low risk of causing contact allergy compared with more complex lip products, and witching to a simple product can sometimes help when your chapped lips aren't improving. LTKBeauty