Summer is upon us, and with it the summons to achieve the perfect tan.

While many choose self-tanners to get a golden look sans sun exposure, an expert warns that there are actually some hidden dangers in a faux glow — if you misuse them.

“Self-tanners shouldn’t be mistaken for sun protection,” dermatologist Dr. Dawn Queen told The Post. And there’s a key mistake to avoid after you spray or slather some on.

Dihydroxyacetone (DHA) is the active ingredient in most self-tanners. It works by reacting with amino acids in the skin’s outer layer to produce pigment and a temporary “tan” or bronzed color.

But when that newly DHA-treated skin gets exposed to sunlight — and UV rays — free radicals can form.

“Over time, repeated UV exposure may contribute to oxidative stress in the skin and potentially to skin aging,” Dr. Queen explained.

So going straight from spray tan to sunshine? Not doing your skin any favors.

And while some sunless tanning manufacturers argue that naturally-derived DHA is less harmful to the skin than synthetic DHA, Queen says there is no meaningful difference, and the “naturally derived” label is mostly a marketing distinction.

Get your sun protection

Self-tanners are still much, much safer than UV tanning — but Queen recommends applying them at night to avoid amplifying UV exposure and lathering up with sunscreen before heading outdoors.

UV radiation penetrates the skin and can damage cellular DNA, leading to short-term effects like sunburn and long-term effects such as premature aging.

Overexposure to ultraviolet (UV) radiation from the sun or tanning beds is the main cause of skin cancer, which kills at least two Americans per hour.

The FDA recommends applying a broad-spectrum sunscreen with an SPF of 15 or higher daily and reapplying at least every two hours, or more often if swimming or sweating. Many doctors up that number to 30 or even 50.

For full coverage, most adults need about an ounce of sunscreen, roughly the amount that fills a shot glass.

Other ways to protect against UV rays include wearing clothing that covers exposed skin, using UV-blocking umbrellas, and avoiding direct sun during peak hours, which are typically 10 a.m. to 2 p.m.

Other skin risks

Beyond DHA, some self-tanners contain ingredients that can irritate the skin.

“These include heavy fragrances, essential oils, certain preservatives (MI, MCI, formaldehyde-releasing preservatives), temporary dyes and alcohols. If you have sensitive skin, it may be a good idea to patch test first,” said the doc.

She added that while most self-tanners can be used without issue, folks with sensitive skin, active eczema, or a history of contact dermatitis may be more prone to irritation.

Even with these risks, she still maintains that a bottle tan bests the sun or a tanning bed.

“From a dermatology standpoint, self-tanners are generally safe when used on the skin and are far safer than UV tanning. The main precautions are avoiding inhalation with spray products, applying them at night rather than right before sun exposure, and continuing to wear sunscreen.”

While she typically doesn’t mind if patients come in rocking a fake tan, she recommends letting your dermatologist know if your glow is bottle-born, as application can cause unusual patterns or discoloration on the skin,

“If you’re coming in specifically for a full skin exam or evaluation of pigmentation, it can occasionally make subtle pigment changes harder to assess. If that’s the reason for the visit, it may help to avoid applying self-tanner right beforehand.”