What Affects the Effectiveness of Sunscreen?
Sunscreen effectiveness depends on more than the SPF number printed on the bottle.
The product needs to be within its usable life, stored appropriately, applied in sufficient quantity and reapplied when necessary.
Heat, prolonged storage and using sunscreen past its expiry date can also affect whether the product continues to provide the protection stated on its label.
Does Sunscreen Expire?
Yes. Sunscreen should not be used indefinitely.
The simplest approach is to check the expiry date printed on the container and replace the sunscreen once that date has passed.
Expiry dates are based on stability testing carried out by the manufacturer. Once a product is beyond its stated expiry date, you should not assume that it will continue to provide the level of protection shown on the label.
In the United States, the FDA advises that a sunscreen without an expiry date should generally be considered expired three years after purchase.
Requirements and labelling can differ between countries, so always follow the expiry information and storage instructions provided on the product itself.
What Temperature Should Sunscreen Be Stored At?
Heat is an important consideration when storing sunscreen.
As a practical guide, sunscreen should generally be kept in a cool, dry place and protected from prolonged exposure to high temperatures and direct sunlight.
Cancer Council Australia advises that sunscreen should typically be stored below 30°C in a cool, dark place.
This is particularly relevant because sunscreen is often kept in places that become much hotter than the surrounding air, such as:
- parked cars
- boats
- closed beach bags left in direct sun
- garages or sheds that become very hot
- bags left beside pools or on hot sand
A parked vehicle can become extremely hot in summer. Prolonged exposure to this type of heat may cause a sunscreen to deteriorate faster than it would under normal storage conditions.
Can Sunscreen Go Bad Before the Expiry Date?
It can.
An expiry date assumes that the product has been stored under appropriate conditions. Repeated exposure to excessive heat or direct sunlight can shorten the useful life of some sunscreen formulations.
The American Academy of Dermatology notes that sunscreen left in direct sunlight or in a hot enclosed space such as a car may deteriorate before its stated expiry date.
If a sunscreen has spent extended periods in extreme heat, it may be sensible to replace it even if the printed expiry date has not yet passed.
Signs That Sunscreen May Have Deteriorated
Do not rely only on the date if the product itself has clearly changed.
Possible signs that sunscreen should be replaced include:
- a noticeable change in colour
- an unusual or changed smell
- separation that does not resolve when the product is shaken as directed
- a significant change in texture or consistency
- damage to the container or closure
If you are unsure whether an old or badly stored sunscreen is still usable, replacing it is safer than relying on uncertain protection.
Should Sunscreen Be Kept in a Cooler?
You do not normally need to refrigerate sunscreen.
When spending a long day outdoors, however, keeping sunscreen out of direct sunlight and excessive heat is sensible. A shaded bag or cooler can help prevent the container from becoming extremely hot.
Follow any specific storage instructions printed on the product label.
Does Cold Weather Damage Sunscreen?
Sunscreen is often stored between seasons, so both excessive heat and unusual storage conditions are worth considering.
The manufacturer's label is the best guide to the appropriate storage range for a particular product.
If sunscreen has frozen, separated or changed significantly in consistency, check the manufacturer's instructions before relying on it.
Application Also Determines Sunscreen Effectiveness
Even a new bottle stored perfectly will not provide its labelled protection if too little sunscreen is applied.
The SPF measured during sunscreen testing assumes a specified amount of product has been applied. In everyday use, people often apply less than the amount used during testing.
For this reason, sunscreen should be applied generously and evenly to exposed skin.
Read our sunscreen application tips for more information about applying and reapplying sunscreen.
Reapplication Matters
Sunscreen does not remain unchanged on the skin throughout an entire day.
It can be removed or reduced by swimming, sweating, towelling, rubbing and normal physical activity.
Reapply sunscreen according to the instructions on the label, particularly after swimming or sweating.
Water-resistant sunscreen is useful for activities involving water or heavy sweating, but water-resistant does not mean waterproof.
Choose Appropriate Sunscreen in the First Place
Storage and expiry are only part of sunscreen effectiveness.
When sunscreen is needed, dermatology guidance commonly recommends choosing a product that is:
- broad spectrum
- SPF 30 or higher
- water resistant when appropriate for the activity
Some national health authorities recommend SPF 50 or 50+ when UV levels require sun protection.
You can compare formulations in our guide to different types of sunscreen, or learn more about how SPF ratings work.
Sunscreen Is Only One Part of Sun Protection
No sunscreen provides complete protection from ultraviolet radiation.
Depending on UV conditions, sunscreen can be combined with other protective measures such as shade, hats, sunglasses and clothing.
For more information about clothing protection, see our guides to UPF ratings and sun-protective clothing.
Quick Guide to Sunscreen Storage and Expiry
- Check the expiry date before using sunscreen.
- If there is no expiry date, follow the relevant guidance for the country in which the product was sold.
- Keep sunscreen away from prolonged excessive heat.
- Avoid leaving sunscreen in a hot parked car for extended periods.
- As a practical guide, storage below 30°C in a cool, dark place is commonly recommended.
- Replace sunscreen if it has significantly changed in colour, smell, texture or consistency.
- Apply enough sunscreen for the labelled SPF to be meaningful.
- Reapply according to the label, particularly after swimming or sweating.
Sources and Further Reading
This page has been updated using current guidance from the U.S. Food and Drug Administration, the American Academy of Dermatology and Cancer Council Australia.
For more information, see our pages on SPF, sunscreen facts, sunscreen ingredients and sunscreen application.
Information on this website is provided for general educational purposes and is not a substitute for individual medical advice or assessment by a qualified healthcare professional.