It is the most skipped step in skincare – and with retinol the one with the biggest consequences. Using vitamin A in the evening and no sun protection during the day means giving away much of the result and risking exactly what you are treating.
Why the two belong together
There are three reasons, and they reinforce each other:
- Vitamin A makes skin more light-sensitive. Accelerated cell renewal means younger skin cells at the surface – and those are more vulnerable to UV damage.
- UV radiation breaks the active down. That is why vitamin A belongs in the evening routine.
- UV causes precisely what you are treating. Up to 80% of visible skin ageing is attributed to sun exposure. Without protection you build up at night what you lose again during the day.
UVA, UVB and why the difference matters
| UVB | UVA | |
|---|---|---|
| Acts on | The upper skin layer | Deeper layers |
| Causes | Sunburn, raised skin cancer risk | Collagen breakdown, free radicals, premature ageing |
| Through window glass | No | Yes |
| In winter | Clearly weaker | Relevant all year |
The protection factor on the packaging refers to UVB only. For UVA look for the circled UVA symbol or a PA rating. And because UVA passes through glass and barely weakens in winter, sun protection is not a summer product – not even if you spend the day indoors.
Which sun protection suits a retinol routine?
The best one is the one you actually apply every day. That is why products combining day care and protection are usually the better choice in practice – one step fewer means it actually happens.
- Advanced Day Ultimate Protect with SPF 50+ combines hydration and protection in one step.
- Advanced Day Total Protect with SPF 30 is the lighter option.
- For the eye area there is a dedicated formulation in Advanced Day Eye Protect.
You will find the full selection under Sun Protection.
How much and when
Sun protection is the last step of the morning routine, after Vitamin C and your moisturiser. For the face, count on roughly two finger-lengths of product – clearly more than most people use. If you are outdoors during the day, reapply.
That completes the morning routine: cleanse, vitamin C, sun protection. Vitamin A follows in the evening. That is exactly the CSA Routine principle on which Medik8 builds its entire range.
Frequently asked questions about sun protection and retinol
Do I need sun protection in winter too?
Yes. UVA radiation is relevant all year and passes through window glass. Anyone using vitamin A in particular should not treat protection as seasonal.
Is the protection in my foundation enough?
In practice, usually not. The amount applied is far less than the amount used to determine the factor. Use a dedicated sun protection underneath.
Can I use retinol in the morning if I apply sun protection?
Better not. UV radiation breaks vitamin A down, which is why it belongs in the evening routine. One exception in the Medik8 range is r-Retinoate Day & Night.
What does PA++++ mean?
It is a measure of UVA protection. Four pluses represent the highest value on that scale. The SPF says nothing about it.
How often do I need to reapply?
If you are outdoors, roughly every two hours. If you spend the day indoors, applying once in the morning is generally enough.
