Do you need a separate sunblock if your moisturizer has SPF?

Summer is near so I am often asked by my friends if they need a separate sunscreen or sunblock for their faces if their moisturizer already has an SPF (an example of such moisturizer with SPF is this cream from TONYMOLY).

Short answer: YES.

Long answer: NO - you don't but there are conditions that must be fulfilled.

No one's too old to start with sun protection.
(Image By Bill Branson, via Wikimedia Commons)

• The moisturizer's PPD or PA rating must be adequate.  Most moisturizers flaunt only their SPF ratings which only addresses the protection against UVB rays (which cause sunburn). But what about protection against early aging of the skin caused by UVA rays? Check your moisturizer's PPD or PA. I personally use PA+++ if I'm going out, else a PA++ is okay as I'm now mostly indoors.

• The correct amount of 1/2 teaspoon is applied for the face and neck. The amount of moisturizer/sunscreen applied is so crucial, applying half the recommended amount would yield less than 50% of the rated protection. For example, at half the recommended dosage, an SPF 50 sunscreen would only have an SPF of 7.1 and absorb only 85.9% of the UVB rays instead of 98%. 

• The moisturizer will be reapplied within the day. Dermatologists recommend every 2 hours application if perspiring or swimming, although no higher bound value is recommended if the user will not "disturb" the sunscreen layered on the face. I'm not really a Maria Clara, so I try to reapply sunscreen when I have the time.

 If you want to read more about sun protection, check out Makeupalley's excellent sunscreen FAQ page.