Sensitive, or reactive skin is a word used to describe skin that feels irritated, gets red, itchy, stingy, or starts flaking, or swelling. This usually happens in response to products or weather.
Symptoms of sensitive skin appear when immune cells in skin go on high alert. The cells "believe" that there is a danger in the environment (even if in reality there is none), and it they need to fight it off with inflammation.
Sometimes this "high alert" reaction is a consequence of an allergy. In this case, the immune system marks a substance as a danger permanently. In other words, skin allergies, once they appear, usually stay with us for life.
More often, the immune system marks a substance as a danger at a particular moment. Dermatologists call this "an irritant contact dermatitis", or irritation. Sometimes you can have an irritant reaction to a skincare product on one day, but be ok with it in a month. (Even though we do not recommend you to experiment with it in real life).
Every individual has a different threshold of "danger" that their skin immune system tolerates without going into a "high-alert", inflammatory state. Some people have very tolerant skin, and can use a lot of products and concentrated actives without a reaction. For others, almost any skincare product seems to trigger a sensitivity symptom. Doctors and scientists do not fully understand what causes the difference. Genetics certainly plays a role. Some people's skin immune system is so sensitive that they are diagnosed with a chronic medical condition like eczema (also called atopic dermatitis).
But even people with a healthy skin usually can experience sensitivity from time to time. Some substances are more likely to cause an irritation than others. For example, fragrances (both natural and synthetic) and preservatives are the most common irritants in cosmetic products.
Irritant reactions are also more likely to happen when the skin barrier is weak. Skin barrier is the very top layer of the skin. It is like a brick-and-mortar wall: dead skin cells on the surface are the "bricks" that are held together with "mortar" of skin natural oils and water-loving substances. When there is a "hole" in this wall, irritating substances can get through it easier, triggering an alarm with the immune system.
Cleansing too much or with too harsh products is often the culprit for the weak skin barrier.
The bottom line is that there are three things you need to do to reduce your skin sensitivity:
Remove the trigger - that is the potential allergens and irritants. This means going through everything that comes in contact with your skin (for example, people often forget shampoo) and checking for potential irritants. Often the most practical thing to do is to stop using most of your current products for a while. (You can choose a very simple non-irritating moisturizer, cleanser and sunscreen to cover the basics). Once your skin becomes better, you can re-introduce your products one by one noting your skin reaction. (If your skin becomes worse after re-introduction of one of the products, you know that the irritant is most likely in it). Canadian dermatologist Dr. Sandy Skotnicki developed this method as a "Product Elimination Diet".
Check your cleansing routine. The best approach is to use a very gentle cleanser, and only cleanse your skin when truly needed. For most people, it is once per day, at night. Less is definitely more with cleansing.
Use a good fragrance-free moisturizer to help re-build your skin barrier.