PEMDAS and ORDER OF OPERATIONS -

WHAT DOES IT HAVE TO DO WITH SKIN CARE?

 

By Dr. Deanne Mraz Robinson



 

Anyone, Bueler, anyone?

 

Remember PEMDAS, the pneumonic to help us remember the order in which to do math problems? It gave us a framework to arrive at the correct answer if we did things in the right order (parenthesis, exponentials, multiplication, division, addition, subtraction). Well, if only skincare was that easy. I am always getting asked, ‘what do I put on my skin first’, ‘how do I layer multiple products’, ‘what should be the last thing I apply’? What about if you throw a prescription into the mix?

 

Skincare is not quite as scientific as mathematics. Many times it is more of an art than a strict science, but there are some good rules to follow about what order to apply products.   Let’s look at morning and night time separately and touch on the basics.

 

AM
Good morning, sunshine.  I wouldn’t be doing my duty as a dermatologist if I didn’t mention here that EVERYDAY, be it rain, sun, snow, or shine, we ALL need sun protection. Sunscreens come in two general forms, physical and chemical blocks. Physical sunscreens are primarily zinc oxide and titanium dioxide and work by reflecting the UV rays off the skin. Chemical sunscreens, such as avobenzone, homosalate, octinoxate, and oxybenzone, absorb the UV radiation and change it to heat, which is then released from the skin. Patients always ask me what my favorite sunscreen is and I always say whichever one you will wear. For that reason, I leave it to you to decide which form of sunscreen you wish to apply. (I personally only wear physical sunscreens as I prefer its mechanism of action for protecting skin).  Depending on the type of sunscreen you choose, it will affect the order in which you should apply products…..

 

  1. Cleanse. Always start the day with a clean slate.

  2. Toner (if you use one).

  3. SPF if using chemical sunscreen. Again, as chemical sunscreens work by absorbing the UV energy into the skin, it needs to be able to be absorbed to do its job.

  4. Prescription or topical spot treater. This is when you would apply your prescription for rosacea, acne, or dermatitis. I always remind patients that in order for your prescription to work to its fullest ability, you want to apply to clean skin before other products.

  5. Antioxidant serum. When layering from here on out, remember to start light and build to heavier products. Makes sense, right? If you apply something heavier first, the thinner topicals won’t be able to penetrate. Antioxidants are a perfect pairing for the morning as they help protect and repair against UV radiation, environmental stresses, excessive blue light, free oxygen radicals, etc. IE, all the stuff that injures and ages your skin. Our Antioxidant Super Serum is ideal for daily protection and anti-aging benefits. (For more information on the importance of topical antioxidants, check out our blog post on this topic.)

  6. Moisturizer. Go with a gel and/or oil free moisturizer if you’re acne or rosacea prone. For drier skin, select one with ceramides to help rebuild the skin barrier and effectively hydrate. 

  7. SPF if using physical sunscreen. Quick review, as physical sunscreens work by reflecting the UV rays off the skin, it should be the last thing on your skin. Remember, you need to reapply sunscreen every two hours to truly protect yourself. This is another reason I opt for physical sunscreens, eliminating the need to rinse and repeat for reapplication. I use a combination tinted, physical sunscreen which doubles as makeup, and then I reapply with a brush on mineral sunscreen. I find this to be the easiest and most manageable way to stay sun safe.

PM

Here comes the real magic. Our skin follows a circadian rhythm, just like our body. During the day, our skin is busy protecting us from the sun and environmental stresses and at night it is repairing and preparing for the next day and our skin care should echo that.

 

  1. Cleanse. Get the day off your face.

  2. Exfoliator. Night time is a good time to exfoliate, just remember less is more. If you are using an exfoliative tool or gritty cleanser, once to twice per week is enough. If you over exfoliate, your skin can get irritated.

  3. Prescription or topical spot treatment. This is the time to apply your retinoid/retinol, or acid-based products. Remember that topical retinoids work by increasing our cell turnover and can make us more apt to be sun sensitive. Also, retinoids are broken down by the sun, another big reason to apply at nighttime.

  4. Antioxidant serum. If it wasn’t clear by now, I am a huge antioxidant fan. Many antioxidants such as vitamin C don’t only protect, but can also help repair damage incurred during the day. As such, I reapply my antioxidants at night.

  5. Serum. Make it work for you. I suggest serums that are hydrating and can help support skin barrier function. Our B5 Hydrating Serum, with Vitamin B5, Hyaluronic Acid and Green Apple Extract is a great option for this!  

  6. Moisturizer

  7. Eye cream. Apply gently to this area.

  8. Oil - if you insist. I haven’t found a facial oil that I love as I find that they can be very clogging and worsen acne. But if you have one you love, apply it last as other topicals likely won’t penetrate through

 

Well, there you have it – my playbook for skincare PEMDAS. Again, this is an art and not a science, but I hope I shared some good pearls of wisdom on product layering. If you have questions, get in touch via www.purebioderm.com or www.moderndermct.com

Thanks!