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Nowadays, there are so many sunscreens on the shelves it is sometimes difficult to know which is the best one for you and for your lifestyle.  If you are confused about the multitude of sunscreen options available today, we at Elite MD are committed to helping make sense of it all for you.

What is the difference between Physical and Chemical Sunscreen?

Physical vs Chemical Sunscreen.  Sunscreens are broken down into generally two categories: physical and chemical ones.  Physical sunscreens use physical UV filters, while chemical sunscreens use chemical filters to protect the skin from harmful ultraviolet radiation.  There are also sunscreens that combine the active ingredients from these two types, and may be referred to as “hybrid” sunscreens.  Here, both physical and chemical blocks are working together to protect the skin from the potentially harmful rays of the sun, in combination.  Physical sunscreens, such as titanium dioxide and zinc oxide, protect your skin from the sun by deflecting or blocking the sun’s rays from reaching the skin…think of it as an invisible “force-field” layer.  Chemical sunscreens, such as avobenzone, octinoxate, and helioplex just to name a few, work by chemically absorbing the sun’s rays.  Some chemical sunscreens act as filters to scatter ultraviolet rays, but the majority act to absorb them.

Physical Sunscreens.  Physical sunscreens are generally stable, and are generally safe for the skin.  Titanium dioxide and zinc oxide are the main two ingredients in commercially marketed blocks on the market.  Titanium dioxide is generally well tolerated by most people, protects primarily against UVB rays (and part of the UVA spectrum), and is FDA approved and safe.  A minority of people may not tolerate titanium dioxide (those who experience irritation with mineral cosmetics for example, may have this ingredient as the culprit).  Zinc oxide, also stable, protects against the entire spectrum of UVA and UVB rays, starts protecting immediately upon application, and may be used on delicate skin (it is the main ingredient in diaper rash cream, and is deemed safe even for babies over 6 months old).  A primary complaint in the past had been that these physical sunscreens could leave a white cast or tint on the skin, however most products on the market today have been expertly formulated that this is much less of an issue and many have elegant application and disappear into the skin quite readily.

Chemical Sunscreens. Most are photo-stable, but some are not.  Avobenzone, a commonly used chemical sunscreen, is notoriously unstable, but can be stabilized when formulated with other UV filters. Most sunscreens containing this ingredient are nowadays much more stable than in previous years.  Chemical filters can in general be more irritating to the skin, may cause stinging if they get into the eyes, and a few may cause allergic reactions on the skin (irritant contact dermatitis).  That said, many argue that chemical filters may offer more coverage against UVA and UVB rays than physical sunscreens, but this range of protection is very ingredient-dependent.  A drawback of these sunscreens is that one must wait a full 20 minutes after application for the chemicals to be absorbed into the skin, and for effective sun protection.  Typically, these are colorless and odorless, and are generally safe to most people.  Many chemical filters have not been FDA approved in the United States, but are currently available in other countries. With advances in the sunscreen market of recent years, you can expect to see many more of these in the stores over the next few years.

By Dr. Sonia Badreshia-Bansal