SIMPLIFY.

“Less is more” is a healthy philosophy for pretty much everything in life.
In food, less processed means more nutrients and less junk. Studies show that mindfulness — clearing the mind of clutter and focusing on the now — has significant health benefits for the brain and aging. In skincare, simple formulations with as few ingredients as possible minimize the risk of cross reactions — it’s a golden rule of hypoallergenicity. Plus, sticking to fewer products from fewer brands means there’s less guesswork involved when identifying what could be causing a reaction or acne.
“Less is more” helps doctors more easily identify what could be the cause of a problem. Frequently, the first step of allergy or contact dermatitis management (often, along with a patch test) is an “elimination diet” (our popular, ultra-reliable 7-Day Skin Fast). In the Skin Fast, you’re asked to stop using all products — except a very, very controlled few — for 7 days. This helps skin return to its most non-irritated state, so that when new products are slowly introduced (one every three days or so), problem products can be more accurately isolated.
The same applies to acne: acne can have several causes and certain types of acne can take days to develop…making it almost impossible to accurately identify which product is causing the acne when using many different ones.
Having fewer ingredients in a formulation is a best practice in hypoallergenicity…so much so that one of the quickest ways to spot a high-risk product is to look at how many ingredients it has: the longer the list, the higher the likelihood of reactions.
In addition, using multiple products can lead to over-treatment and drying of the skin…getting it to a borderline-irritated state so that anything new applied (whether or not you are actually allergic to it) could trigger a reaction.
This is why doctors tend to recommend sticking to few products and, ideally, from the same brand. It is impossible to ensure how products are made from one brand to another, ingredients can have different raw materials (some pure, some with additives such as trace amounts of preservatives or allergens), and many formulations are outsourced to third-party manufacturing facilities where vats can be used for mixing many different formulations, including those with allergens. Check out Why Sticking to One Brand Is Safer (an interview with EczemaBlues.com) for more on why using products from different brands can make the management of complex skin conditions difficult.

For more on hypoallergenicity and how less is more, check out:

HYPOALLERGENIC: What is it Really?
Why Sticking to One Brand Is Safer

For more on reactions:

Reactions: About, Allergic, Irritant, Sudden, Prevention, Using VMV & Other Products, etc.
Mythfoliation: If I Get a Reaction, The Last Product I Applied Is The Problem