Ask A Derm: Reapplying SPF, and Ideal Hair Washing Schedule

Summer by Tom Bianchi
Photo Credit: Tom Bianchi
The Green Derm is back to weigh in on your questions.

Show of hands for all those who reapply their sunscreen throughout the day. Chances are, that isn’t many of us. Although many of us know we’re supposed to reapply sunscreen throughout the day, it just doesn’t seem to have turned into something any of us really do. Then, there’s hair washing. How often should we do it? Too often and it can dry out hair and imbalance scalp, not often enough and it can be a greasy mess, and create other issues. We’re in luck, because The Green Derm is here to answer these questions as he always does, with a realistic and measured response.


How often should we reapply sunscreen, and how should we do it?

Assuming we’re using something that is at least SPF30, the general recommended reapplication schedule is around every two hours. Of course, this isn’t a hard and set duration. Factors like activity level, and actual sun exposure will all play a part. If you’re out and about in direct sun, or swimming at the beach, it’ll be better to stay on the safe side with frequent reapplication. On the other hand, if you’re indoors, away from direct sun, and just watching tv or in front of your laptop, you can be more relaxed about it.

With this said, there are several reasons why we do not reapply sunscreen. The reasons I hear most often are:

1. I already have my full routine (skincare and makeup) done, and I’m afraid this will mess it up.
2. I feel kind of gross already, and am concerned about putting another layer of product over my face.

These are logical concerns, and I agree that reapplying can be kind of tough to figure out. Luckily, there are good products designed for this.

Photo Credit: SuperGoop!


SuperGoop! (Re)setting Refresh Mist SPF40 is a fantastic way to reapply throughout the day without messing up your routine. It was designed precisely to be a resetting and refreshing mist sunscreen that doesn’t require rubbing onto the skin again, which means everything is kept in place as your reapply with a nice, protective SPF40. Once on your skin, the SPF is really, really light as well, and it even has ingredients to help “reset” makeup to keep it in place throughout the day.

Photo Credit: YÜLI

YÜLI Panacea Elixir is a great pre-application step for those mid-day touchups if you feel your skin is already a bit ‘gross’ for lack of a better word. This is because Panacea Elixir is designed for ‘active’ skin that may experience congestion, overactive pores, excess sebum production, so it uses herbs that have proven benefits to fend off the troublesome bacteria in the biome, and clarify skin. If you’re not able to wash up and reapply your entire regimen, this is a great way to take care of those concerns and make SPF reapplication easier.


How often should I wash my hair?

This one is tough because it really depends on personal factors. Firstly, what your hair and scalp situation is. Oilier hair, and scalp that is prone to itchiness should be washed more regularly. And then on your activity level. Those who workout regularly should wash more as well. It’s truly a balancing act as you shouldn’t wash your hair too much, yet you should wash it often enough that it’s clean. 

As a general approach, men do need to wash their hair more than women which is why those “once a week” approaches don’t really work for men. This is because we tend to produce more sweat and sebum, and have more active hair follicles due to testosterone. The best way to figure out the frequency that you need is to start on a every-three days cycle. If you find your hair getting greasier, or your scalp more irritated, set your routine to a every-two days cycle. If on the other hand your feel your hair is getting drier, or your scalp is flakey and tight, extend to a every-four or every-five day cycle. Usually people end up finding they wash their hair 2-3 times a week. There is no right or wrong, only what works for you.

I personally prefer to under wash rather than over wash because I find it’s better for the scalp biome, and hair is healthier when there are some natural oils. If I ever go longer than I should, and feel my hair getting a little uncomfortable before my next wash, I always have a dry shampoo ready. My favorite is Klorane’s Dry Shampoo with Oat Milk which soaks up excess oils, and has oat milk to soothe the scalp. It’s an immediate spray of relief that will tide you over until your next wash.

As for shampoos, I always go with a green beauty shampoo here because I find them to be much gentler on hair and scalp. I think Ursa Major’s Go Easy Daily Shampoo is an under-the-radar gem that everyone I recommend it to ends up loving.


If you have any other questions, send them to here!


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