Robert Smith, MD, dermatologist and assistant professor of dermatology at Johns Hopkins Medicine in Baltimore, MD, as told to Matt McMillen
As a dermatologist, I frequently see patients with eczema, also called atopic dermatitis, who develop patches of light or dark skin following a flare. Let’s talk about why that happens, what you can expect, and what treatment options are available.
What causes my skin to lighten or darken?
An eczema flare can leave behind a “memory” on your skin, called dyspigmentation. When the skin becomes darker, it’s called post-inflammatory hyperpigmentation. A lighter patch is called post-inflammatory hypopigmentation.
These happen when inflammation irritates your keratocytes (the top layer of skin cells) as well as your melanocytes (the cells that produce the pigment melanin, which gives your skin its color).
Sometimes, that irritation causes your melanocytes to stop working temporarily, which results in whitening of the skin. Other times, the irritation causes the transfer of melanin from your melanocytes to other skin cells. This results in patches of hyperpigmentation, or darkened skin.
Very severe inflammation can force pigment down into the second layer of skin, called the dermis. That can lead to even more pronounced or longer-lasting hyperpigmentation.
Speaking of causes, one thing I always stress is that medications, such as topical steroids, do not cause these light or dark patches. That’s a concern I often hear from my patients. I explain to them that it’s untreated eczema, not their medication, that causes discoloration.
Who is most likely to get such light or dark patches?
Everyone can get hyper- or hypopigmentation after a flare, but people with darker skin have more pigment and are at a greater risk of having severe hyperpigmentation. But you can have a dark skin type and end up with a light mark. There’s not a great way to predict who’s going to get which. In fact, I have patients with eczema who have both light and dark patches on their skin.
In patients with lighter skin types, dyspigmentation can be a little different. Hyperpigmentation often looks more red than dark, while patches of lighter skin may be less noticeable.
Are these patches the same as scars?
No. That’s another common concern, but what they’re seeing is not a scar.
True scarring involves damage to deeper skin structures, while eczema affects the epidermis, the top layer of skin. In severe cases, intense scratching during a flare could damage the deeper skin and cause scarring. However, this would result from scratching, not from the eczema itself.
Can you prevent the skin discoloration that occurs after an eczema flare?
It’s mainly a matter of preventing such flares from happening in the first place. That’s the most important thing that we can do.
In theory, if you have an acute flare, shutting it down early may help reduce discoloration, but I would expect that you’re going to have some discoloration just because you’ve had a flare.
I do think that the more intense the flare, the more severe the reaction, or the longer the flare goes untreated, the longer the pigmentary changes are likely to persist.
How long do these patches of light or dark skin take to return to normal?
There’s no perfect math to calculate how long dyspigmentation will last. We can’t say something like, if you have a flare for seven days, things will take only a month to get better. But again, as a general trend, the longer the flare goes untreated or the more severe it is, the more intense and lasting the pigmentary changes are likely to be.
Typically, you should expect the pigmentation changes to last weeks or months, but they can take years to clear up in some cases. Keep in mind that eczema affects people differently, so your experience won’t be the same as that of someone else with the disease.
How does treatment for flares differ from treatment for post-flare skin changes?
Prevention of flares is the priority for avoiding hyper- or hypopigmentation. The best thing you can do is to stick with your daily skin care routine, a key part of your treatment plan. This includes using a really good moisturizer to maintain the barrier of your skin, which can help prevent further eczema flares. If a flare begins, see your dermatologist, who may prescribe topical steroids or other treatments to calm the inflammation in your skin.
In addition to maintaining your treatment plan, it’s really important to limit your skin’s exposure to the sun with sunscreen or sun-protective behaviors. This is especially true for hyperpigmentation. Sun exposure can make dark patches even darker. One of our tools to interfere with that process and potentially help resolve dark spots a little more quickly is using different kinds of sunscreens. I recommend sunscreens labeled ‘broad-spectrum.’ These protect against both ultraviolet A (UVA) and ultraviolet B (UVB) rays from the sun.
Look for a broad-spectrum sunscreen that contains iron oxide, which offers additional protection against the visible light spectrum. Some research suggests that sunscreens with iron oxide may help lighten dark spots a little faster than other sunscreens.
There are indeed some prescription whitening creams out there, but they work very slowly. It’s also really difficult to use them over large areas of the body. And depending on the kind of hyperpigmentation you have, they may not be helpful at all. A lot of hyperpigmentation happens in the deeper layer of skin called the dermis, and our topical prescription medications don’t really get there. So, the most important therapies really are prevention and sunscreen.
For patches of lightened skin, sunscreen or sun protection probably is not going to be as useful as it is for darkened skin patches. But barrier protection with really excellent moisturizers to prevent new eczema flares is just as important. As a general rule, I find that post-inflammatory hypopigmentation resolves or seems to resolve more quickly than hyperpigmentation, though this is not true in all cases.
If you do develop a scar due to scratching, can anything be done to repair the skin?
First, to prevent scars, you need a flare treatment plan that you can follow if your eczema becomes active. I always tell patients it’s virtually impossible not to scratch an itch, and it’s my job to help you get rid of the itch. That’s what our medications are designed for. Following your plan can shut down your itch so you don’t need to scratch. And if you don't scratch, you’re less likely to cause deep skin damage that could lead to long-term changes in the skin.
If you do have true scars, there are some treatments, such as over-the-counter silicone scar tape, silicone scar gel, and prescription injections. What’s best depends on the type of scar, whether it is flattened (or sunken into the skin) or raised or thickened (called hypertrophic scars). Your dermatologist can decide what’s best for you.
But to be honest, I rarely see scarring from eczema.
How can you manage the emotional burden of these visible patches?
When you have a really visible dyspigmentation from a flare, it’s like adding insult to injury. Sometimes, for some people, the discoloration is more worrisome than the flare, and it can have a huge impact on their quality of life. We want to make sure we’re empowering people with visible differences, but at the same time, we acknowledge that having those visible differences comes with a toll.
We try to help them manage it by validating their feelings. I understand that this is a big deal. I don’t dismiss the impact of these skin changes or the fact that they may last for a while. But I encourage them to keep in mind that these changes will not last forever. For some, that may be enough.
Pay attention to your feelings. Are they interfering with your daily routine or social life? Are those feelings taking up a good amount of your daily brain space? If so, I recommend working with a therapist who can help you manage those feelings, which may be symptoms of depression or anxiety.
What should you discuss with your dermatologist at your next appointment?
Make sure that you and your dermatologist are on the same page about what you’re doing to manage and prevent eczema. If you’ve had a flare despite closely following your treatment plan, ask if your plan needs adjustment. There may be more effective treatments for you to prevent future flares. Also, review your plan for what to do if you have a flare. Did it work well for your most recent flare? Finally, ask your dermatologist how best to manage the leftover dyspigmentation, both the physical and emotional aspects of it.
