This summer, Mila Kunis, Ashton Kutcher, Monica Padman and Dax Shepard set off a social media storm about showering. Kutcher said on the Armchair Expert podcast that he washes his armpits and crotch with soap daily – and everything else with water. Is that good for you? Dermatologist Ronald Sulewski, MD, is here to give you the science on showering.

How often should you shower? 

So are you showering too much, too little or just enough?

The answer is: It depends.

"For specific skin conditions, it is possible to shower too often or not enough," says Dr. Sulewski. "For instance, people who have dry skin conditions like eczema do not need to shower daily." And technique matters on dry skin, too. Instead of enthusiastic (and abrasive) scrubbing that can worsen dry skin, try gentle lathering with your hands. Skip loofahs, washcloths and exfoliating products.

But, if your skin is on the oily side, you should shower more often. "On the opposite end of the spectrum, we advise patients who deal with acne to shower and, in particular, wash their face daily or a couple of times a day. This can help keep breakouts at bay," explains Dr. Sulewski.

It also depends on your personal preference. Do you feel better with a daily showering routine? Or would you rather skip some days?

Do you need to use soap when you shower? 

"Use soap on your groin, your armpits and your feet – the areas that are prone to bacteria and can get smelly," says Dr. Sulewski. Any other areas are likely good with water. (Looks like Kutcher's showering style is dermatologist-approved.)

How often should you wash your hair?

"When it comes to washing your hair, that is very individual," says Dr. Sulewski. "I've had patients that need to wash their hair daily or it becomes too greasy, whereas some only wash their hair once every two weeks." 

When you need to wash your hair is driven by genetics, as well as the texture and thickness of your hair. For example, African American hair usually needs less frequent washing. Our new Skin of Color Dermatology clinic features dermatologists who know how to care for a wide variety of hair types.

That long, hot shower might be drying you out

The length and temperature of your shower can affect your skin as well. "Showering in too hot of water and for too long can really dry out your skin. Generally, I recommend showering for a shorter period – think 10 minutes instead of 20 – and in warm, not hot, water," says Dr. Sulewski.

It seems a bit like an oxymoron, but staying in the water too long actually dehydrates your skin. 

That's why we recommend you put moisturizing cream on immediately after stepping out of the shower. This helps to lock in the moisture and rehydrate your skin.

"Lotion is less moisturizing than cream," says Dr. Sulewski. "The thick, goopy creams are the best for adding moisture. Some of the best brands are Cerave, Cetaphil and Aveeno, but there are many great ones."

Can you train your skin or your hair to be less oily or need less showering? 

If you switch up your showering routine, you might hope your body will follow along.

But, Dr. Sulewski says, your skin type is usually your skin type. "There are instances where people have hormones that are out of alignment and once their hormones get under control then we see improvement in their hair and skin. But otherwise, it is hard to ‘train' your skin." 

Showering 101

To recap, how often you should shower depends on:

• Your unique skin type (dry vs. oily)
• Any skin conditions you may have
• Personal preference

To keep your skin hydrated, healthy and clean:

• Use soap on your groin, armpits and feet
• Shower for 10 minutes in warm (not hot) water
• Apply a thick cream immediately after you step out of the shower