When it comes to protecting your skin from harmful UV rays from the sun, sunscreen is key.

But what about makeup products and moisturisers that contain SPF sunscreen — how much protection do they provide?

According to an expert, the answer is that the products offer limited protection from the sun.

"I think the answer is it offers some protection, and any protection is better than nothing. The issue with makeup having sunscreen in it is it's not a primary sunscreen — and it's how people use it," New Zealand Skin Cancer Doctor Society vice president Dr Megan Reilly told Seven Sharp.

"I, for one, don't use makeup on my ears, and a lot of people don't use makeup that has sunscreen in it down the sides and the back of their neck. It's just not quite as effective as a primary sunscreen."

Reilly also had some tips on applying sunscreen and a moisturiser or makeup that includes SPF to the skin.

"I always recommend to my patients that they use a really good broad-spectrum sunscreen, and they apply that. They actually need about a teaspoon of sunscreen to apply to their face and neck to be effective," she said.

"They should wait about 20 seconds for that to soak in, and then they can apply their makeup over the top. The great thing about makeup with sunscreen in it is that can mop up any bits that they've missed. It's almost like an extra insurance policy."

How often we reapply sunscreen during the day is also important.

"Our general recommendations are that you reapply your sunscreen every two hours," shared Reilly.

"It's probably not that practical to reapply your makeup every two hours. As long as you've put your broad-spectrum sunscreen on in the morning, and you've put your makeup with SPF on, you'll probably get a decent amount of time out of it.

"But it would be great if you went out of the office at lunchtime and topped up with putting your makeup on, then you're getting a bit of SPF," she added.

"It's good to remember other forms of sun protection such as wearing a hat, seeking some shade and wearing some long sleeves if you're able."

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