Other combination therapies may lack convenience but are also effective. In the patient with comedones and inflammatory lesions, a comedolytic agent such as tretinoin, adapalene or azelaic acid may be combined with benzoyl peroxide or a topical antibiotic. The combination of clindamycin and tretinoin causes less irritation than tretinoin alone. 30 In using tretinoin and the benzoyl peroxide–erythromycin combination together, the patient should alternate the products daily for two weeks to minimize irritation. When agents that cause irritation are used, patience is necessary, but the results may be well worth the wait.
NAD + acts as an electron carrier that helps with the interconversion of energy between nutrients and the cell's energy currency, ATP. In oxidation-reduction reactions, the active part of the coenzyme is the nicotinamide. In NAD + , the nitrogen in the aromatic nicotinamide ring is covalently bonded to adenine dinucleotide. The formal charge on the nitrogen is stabilized by the shared electrons of the other carbon atoms in the aromatic ring. When a hydride atom is added onto NAD + to form NADH, the molecule loses its aromaticity, and therefore a good amount of stability. This higher energy product later releases its energy with the release of a hydride, and in the case of the electron transport chain, it assists in forming adenosine triphosphate . 
You can buy some topical corticosteroids "over-the-counter" without a prescription. For example, for dermatitis, you can buy the steroid cream called hydrocortisone 1% from your pharmacy. Do not apply this to your face unless your doctor has told you to do so. This is because it may trigger a skin condition affecting the face ( acne or rosacea. ) Long-term use may also damage the skin. On your face this would be more noticeable than the rest of your body. So usually only weak steroids are used on the face. Those which are suitable are prescription-only.