Sunscreen & Rash

Since posting Natural Sunscreen Review, Part 2, I’ve seen an upcropping of posts about and pictures of terrible skin reactions to Neutrogena Pure & Free Baby Sunscreen – a sunblock that I favorably reviewed. The recent influx of circulating testimonials, some written in 2010 and now reappearing, about rash caused by Pure & Free raises doubt about the product’s safety. It appears that some people are having allergic reactions for some reason. What exactly is going on? This question is one that deserves explanation and clarification.

What’s the Issue?

Most of us have either personally experienced or witnessed an allergic reaction on the skin. Some cases involve seemingly innocuous, topical hygiene products. There’s an emergent allergen in our midst – methylisothiazolinone (MI), a common preservative found in many water-based toiletry products marketed to both children and adults. Pure & Free contains MI, and the general consensus in the research is that it is responsible for recalcitrant allergic contact dermatosis (ACD), or rash, secondary to Pure & Free. Some researchers disagree.

In fact, Methylisothiazolinone was named “Contact Allergen of the Year” for 2013 by the American Contact Dermatitis Society.


Kathon CG is the trade name for a 3:1 combination of methylchloroisothiazolin one/methylisothiazolinone (MCI/MI), which is produced by Dow Chemical Company. MCI/MI has been used as a preservative since the 1980s in the United States. However, as the incidence of ACD to MCI/MI steadily rose over the years, the FDA imposed restrictions on concentrations of the combination preservative in cosmetics and household products. In turn, the restrictions prompted manufacturers to produce more products with MI alone and in higher concentrations.

MI may trigger such reactions if found in moistened baby wipes, hair products, soaps, bubble baths, and sunscreen.

Why Is Pure & Free Getting So Much Attention?

Like a past trend coming back into fashion, consumer shock and concern about Pure & Free has resurfaced. It has spread through social media sources including Instagram, Twitter, and Facebook. Blasts warn against use and even sale of it. This negative attention and outrage about a potential side effect of Pure & Free, in particular, seems heightened by the fact that it is marketed as a natural option for those with particularly sensitive skin, including infants.

Here’s an example of a circulating parental warning on Facebook:


For most people, the product causes no reaction.

If you’re not sure whether you’re sensitive or allergic to MI, you may want to test Pure & Free on a small area of skin before you smother yourself in it. The elbow crease is a popular place to test because the skin there is thin, sensitive and relatively inconspicuous. Rub in a pea-sized amount of it, or any new product for that matter, just once a day for three days. If no rash occurs, it probably is okay to use it more broadly. If rash does occur, however, it’s a good idea to avoid products containing MI.

How and Why Do These Rashes Occur?

The current theory is that MI produces a secondary ACD in the context of skin inflammation and degradation. What does that mean?

I think this concept is easier to appreciate if we liken it to the common phenomenon of diaper rash. In the perianal region of a sensitive buttock, irritant contact dermatitis may result from a nonspecific, pro-inflammatory, innate immune response to the fecal enzymes of residual stool. Innate immunity refers to non-antibody defense mechanisms that come into play immediately or within hours of an antigen’s appearance in the body. (An antigen is the causative ingredient.) These automatic mechanisms include physical barriers such as skin, chemicals in the blood, and immune system cells that attack foreign cells in the body.

Thus, fecal material initially serves as a skin irritant, but in many cases, it may gradually become an allergen. Subsequent repeated exposure to the fecal enzymes may eventually lead to skin sensitization, resulting in an allergic contact dermatitis. Allergic dermatitis involves adaptive immunity, a delayed, antibody driven immune response that manifests after an initial exposure once sensitization occurs.

Similarly, the moment that an irritant ingredient found in a skin care product hits the skin, it may inflame it – with a resulting irritant contact dermatitis. And, with repeated use, which could be immediate with the very next exposure or delayed until after a few applications, this ingredient may actually cause an allergic reaction. This occurs because the body has created antibodies to a particular antigen; it’s a learned response that will continue to repeat itself.

Irritant vs. Allergic Reactions

Although they vary in degree of severity, essentially, irritant and allergic dermatoses look the same on the skin. These rashes can be scary, particularly when they appear on children. Generally, such rashes are confined to application sites only, but allergic dermatoses may involve some untouched, peripheral skin due to the skin’s inflammatory process. Think of this as inflammatory recruitment of skin that is simply in the wrong place like an innocent bystander.

Irritant contact dermatitis typically hurts, commonly described as a burning sensation. Allergic contact dermatitis may itch and/or burn, sometimes described as a tingling burn-itch sensation that intensifies with scratching.

How to Resolve Rash

WebMD supports the notion of seeking medical attention for any rash that persists, worsens, recurs, or is annoyingly symptomatic. In the case of a suspected contact dermatitis, determining and eliminating the irritant or allergen is critical. Needless to say, a thorough and often exhaustive history of hygiene regimens and toiletry use is essential to diagnosis. If and when all else fails, a dermatologist or an allergist may perform PATCH testing on the skin to elucidate an allergen.

Merely ceasing the use of the causative agent may provide clearance, in some cases without any therapy. However, in severe or symptomatic cases, topical corticosteroids may be necessary. It’s important to note that terms such as “gentle,” “sensitive,” “organic,” or “hypoallergenic” are used for marketing purposes. Products labeled as such may still contain common allergens and result in allergic reactions. For example, Huggies baby wipes also contain MI.

Take-Away Message

The ACD-afflicted and their parents have raised a lot of awareness about the potential for rash with Neutrogena Pure & Free Baby Sunscreen. But I hope that this post highlights the importance of knowing that the preservative MI appears to be the actual allergen – for the minority, and certainly not for all, of us.

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Categories: Children's Skincare, General, Skin Cancer, Sun Protection


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