A dermatologist weighs in on an Aussie mum's viral tip about sunscreen.

A leading Australian dermatologist has weighed in on the validity of Brisbane mum Connie-Lee Swadling’s viral Facebook post on choosing the right sunscreen.

The post, which was shared more than 14,000 times, has since been deleted, but Connie-Lee posted it after being given advice from her dermatologist that she felt compelled to share.

The dermatologist advised her to ignore the SPF rating on popular sunscreens and instead study the ingredients.

“I’ve recently had a mole checked, everything is fine but he asked what sunscreen I used,” Connie-Lee wrote.

“I replied with the banana boat spf 50+ spray on for myself and banana boat sensitive spf 50+ roll on for my kids. He replied with shaking his head (sic)!”

Her dermatologist then told her to "ignore the 30, 40, 50 + on the front" because it's not the most important factor in determining the effectiveness of sun protection.

"My mouth dropped as this is what we are all taught to look for!" she shared.

"He then proceeded to notify me of the ingredients on the back and said for it to actually protect your skin it needs to have titanium and zinc in it (both of which can not turn into spray form so they never leave the can to protect your skin when applying the spray sunscreen.)"

But Associate Professor Rosemary Nixon, from the Australasian College of Dermatologists, told Mamamia that the most effective products on the market have a combination of both physical and chemical sunscreens.

"Physical sunscreen sits on the outside of the skin and it reflects and blocks the UV from getting into the skin. It acts as a barrier layer, and that’s why it’s always going to be more effective against a more broad spectrum of UVs," she said.

"Chemical sunscreens absorb UVs. That’s why you’ll often see a number of chemicals written down [in the ingredients list]. Virtually all sunscreens will have a combination of [physical and chemical] sunscreens."

Nixon advised against ignoring a product's SPF rating.

"We have a whole industry that has worked out the appropriate SPF [ratings] and there are stipulations that have been worked out by numerous committees," she said.

"The higher SPF rating means the product has been rated to the current standards, and they are based on both UVA and UVB protection. An SPF product will undoubtedly have a component of both physical and chemical sunscreen."

She advised that it's best to avoid using chemical sunscreens on children under 12 months.

"For children under 12 months, the recommendation has always been to have a physical sunscreen rather than a combination of chemicals," she said.

CEO of Cancer Council Australia, Professor Sanchia Aranda, said no matter what sunscreen consumers use, application is key to getting the best sun protection.

"Apply sunscreen liberally - at least a teaspoon for each limb, front and back of the body, and half a teaspoon for the face, neck and ears," she told Mamamia.

"Most people apply less than half this amount, which means they get far less protection than the SPF as stated on the bottle.

"Sunscreens need to be applied liberally to achieve the SPF protection claimed on the label."

Make sure you use five forms of sun protection this summer... we want to see your #SunSmart5 #SkinWeek

A photo posted by Cancer Council Australia (@cancercouncil) on Nov 21, 2016 at 10:18pm PST

Professor Aranda also said that sunscreen should always be used in conjunction with other sun protection measures.

"Don’t forget to Slip, Slop, Slap, Seek (shade) and Slide (on sunglasses). Physical protection such as shade, clothing and broad brimmed hats are the best sun protection measures for all children, particularly young infants," she said.

"Sunscreen should be the last line of defence and used only on smaller parts of exposed skin after it has been patch tested."