The natural formula in Fever Blister Relief is highly concentrated in shea butter with selected natural & essential oils added. Cold sores and fever blisters are one and the same. Apply Fever Blister Relief to affected area at first sign of cold; early treatment delivers best results. Cold sores usually last about seven to ten days. Fever Blister Relief is for treating cold sores and fever blisters on face or lips. Applying this salve shortens duration of tingling, pain, burning, and itching symptoms. 15 oz No animal has been used in the testing of this product.