How to use Cymex Cream Repeat every hour until the cold sore fades so your lips can feel smooth and supple once more. How Cymex Cream works to relieve cold sores Cymex Cream’s triple action formula actively relieves, controls infection and promotes effective healing of painful unsightly cold sores and dry cracked lips. Urea – softens the outside layer of the skin Dimeticone – keeps the skin moisturised and helps prevent scabs from cracking Cetrimide – is an antiseptic which helps prevent further infection of the broken skin Chlorocresol – also an antiseptic which helps prevent further infection of the broken skin