I would avoidOctinoxate,which is harmful to coral reefs and can cause skin allergies as well asAvobenzone,which can cause high levels of irritation. You also need to avoid Retinyl Palmitate, which does not mix well with the sun. When mixed with the sun, it can be potentially cancerous." Water resistance: For a sun cream to be water resistant, it must have undergone testing to show that it stays effective for at least 40 minutes in the water. After this time, you will need to reapply. Dr Paul Banwell, who runs The Banwell Clinic and is the previous head and founder of The Melanoma and Skin Cancer Unit (MASCU) in East Grinstead, agrees. He told us: "I cannot emphasise enough the importance of selecting a broad spectrum sunscreen, which will protect against UVB and UVA rays. UVB rays cause redness and sunburn as well as skin cancer, while UVA rays can also cause cancer as well as ageing of the skin. Newer sunscreens have infrared (IR) protection too and should be considered." Sun creams to avoid: The warning signs to look out for

For environmentally conscious sun-seekers, this sun cream by Forever Living is the one to go for. It won the best sunscreen category in the Green Parent Beauty Awards in 2021, and it's vegan and cruelty-free. The inclusion of aloe vera and vitamin E is extra moisturising and soothes the skin, and the formula promises to be water resistant for 80 minutes.If you're using sun cream at the beach, apply plenty before swimming, and again when you leave the water. Reef-safe sun creams

For more details on the importance of vitamin D and where to buy supplements, see our in-depth vitamin D guide . Other ways to stay safe in the sun The industry guideline for water-resistant sun creams allows the SPF of a product to drop by 50% after a total of 40 minutes in water. Water-resistance testing also takes place in what is essentially a bath – using tap water. For any product to provide the SPF it claims, you need to apply 2mg per square cm – which means around a teaspoonful of product for your face. And, just as with sun cream, it needs to be reapplied regularly. Physical/mineral products reflect visible light as well as UV, which can make the formulations opaque and leave a white residue on the skin. Some formulations use nanoparticles of titanium dioxide and zinc oxide – the minerals responsible for the residue. Nanoparticles are smaller, and as they scatter visible light – rather than reflect it – the sun creams are transparent. How to use sun creamThis tends to mean that two commonly used chemical UV filters linked to coral bleaching – oxybenzone and octinoxate – aren’t used. Oxybenzoneis another ingredient to avoid as it is easily absorbed by the skin and enters the bloodstream, and it can disrupt your hormones as well as causing terrible harm to the environment. If you're someone who's in and out of the pool or sea when the sun comes out, then this formula from Bondi Sands might be the one for you. It's specially formulated to be water resistant for four hours - far longer than the 40 minute criteria that other water resistant sun creams must meet. It's infused with ethically sourced algae for deep hydration and is, of course, reef friendly too. However, there's no agreed definition of 'reef-safe', research is still ongoing as to the impact of these chemicals, and our tests found many mineral suncreams failed to protect as claimed – so take any claims with a pinch of salt. Kids' sun cream He added, "Other ingredients that may cause reactions include benzophenones, cinnamates and dibenzoylmethane.