Many of us may reach for last summer's bottle of sunscreen to slather our skin, but do you ever stop to consider whether it may have expired?
Scott McGregor, co-founder of We Are Feel Good Inc. and skin cancer and cosmetic physician answers our questions about sunscreen expiry and storage.
How long does sunscreen last? This is a very good question with no simple answer. Sunscreen that has a TGA licence number (i.e. AUSTLXXXX on the front of the bottle) will have been vigorously tested for effectiveness of its preservatives and ability to withstand periods of heat.
Most sunscreens tested this way will last three years if stored in the ideal conditions, or 12 months once opened. Ideal conditions means consistently below 30° and once opened the lid needs to be airtight.
Heat and exposure to air will reduce the life of sunscreen. Exposure to air will promote the introduction of bacteria and other unwanted organisms that will damage the product. This is why a very good preservative system is required.
Can I still use expired sunscreen? It's probably best not to. The problem is that the product will have started to decline in it's effectiveness but you will not be able to tell by how much. So is it really protecting you?
How can I tell if sunscreen has gone bad? It can be very difficult to tell in some cases, but usually the product will start to "separate" - that is, starts to lose its consistency and might become a bit granular. This typically happens with sunscreens left in the car or on the boat for too long, exposed to extreme heat. It will also occur if you leave your sunscreen tube open for a period of time, allowing air to get in.
How should I store sunscreen? Sunscreen should be stored in a cool dry place with a temperature consistently below 30°. Clearly this means not in the car door over summer! Always secure the lid after use to increase the product's life.