For skincare products that seem to be the same strength, why are they so different?

For skincare products that seem to be the same strength, why are they so different?

Dr. Irwin: What is the difference between Refissa tretinoin cream USP 0.05% vs Perrigo’s tretinoin cream USP 0.05%? I have been using Refissa for years, but now I have a problem getting it due to a backlog. I wonder if I can use Perrigo’s tretinoin cream USP 0.05% instead? Many thanks Amy.

Some days I think we all need a degree in chemistry to really understand skincare product labels. I love your question because it really gets back to that issue.

To answer your question, if you really love Refissa (tretinoin 0.05%), I doubt you’ll love the Perrigo tretinion because the base is so much thinner and formulated more for oily skin. Refissa had an almost ointment-like base, and was great for dry skin. For those of you who don’t know, tretinion is just a concentrated version of retinol.

There are a lot of tretinoin products on the market, and they come in gels, lotions, and creams. The lines between these different vehicles are often blurred though. You might have a lotion-like gel or a very thick lotion that works more like a cream. The same is true for lots of other products.

Does it really matter? Having watched patients and myself struggle to replace a favorite now discontinued product, I think it does. Why?  Read on.

Why does the base or vehicle of the product make such a difference:

  • If you want a product that works for dry skin, look for the top 5-6 ingredients to be things like squalene, natural oils, shea butter, and even petrolatum.
  • If you want a product that works for oilier skin, then look for products that have more hyaluronic acid, non irritating alcohols, aloe vera and similar in the top 5-6 ingredients listed.
  • The ingredients most likely to cause skin irritation are preservatives, fragrances, propylene glycol, lanolin and some alcohols.
  • The base affects the bioavailability of the active ingredient too. That tretinoin 0.05% may be somewhat stronger, or weaker, depending on what it’s put in; there’s really no way to tell that as a consumer ahead of time.
  • Natural oils and dry oils are all the rage now, but they can clog pores in susceptible individuals despite the marketing.
  • Creams are maybe the hardest to evaluate without actually buying them because some are more gel-like. Some are light and absorb easily, some mid-weight, and some are very dense and more occlusive.
  • Do samples help? They can help you tell whether you are allergic to it, if the fragrance will work for you, and if the consistency is right for you. Other than that, they aren’t very helpful. It takes 30-90 days to see if a product really makes a difference in the quality of your skin. We all have drawers of them though, and I’d vote for a clean out and dump session twice a year.


Hope this helps!
Dr. Brandith Irwin, MD
Founder of SkinTour & MadisonMD Skincare
Follow my skin tips and travels on Instagram!