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A review of some of the best-selling over-the-counter moisturizers finds that most products contain at least one allergen that could worsen the very skin condition it is designed to treat.

The , in JAMA Dermatology, found that of 153 products, 88% contained at least one allergen of the North American Contact Dermatitis Group (NACDG) series, such as fragrances, parabens, and tocopherol. Most of these contained more than one allergen: 43% contained three to four allergens, and 13% contained five or more allergens.

Over-the-counter moisturizes are often recommended by dermatologists to treat skin conditions, such as atopic dermatitis, allergic contact dermatitis, contact dermatitis, and psoriasis. These recommendations are made by physicians who may not realize they may be exposing patients to myriad ingredients that could possibly cause an allergic reaction.

"The concept of hypoallergenic as perceived by lay people and physicians is often misunderstood," said the study's senior author, Jonathan Silverberg, MD, PhD, MPH, of Northwestern University Feinberg School of Medicine in Chicago. "For instance, physicians who recommend certain products to patients believe that the patient will not be allergic to them and, therefore, the products will be safe to use. But in fact, with enough exposure and an underlying predisposition, patients can develop allergies to many of these personal care products."

The team reported: "Our analysis of best-selling moisturizers across three major online retailers reveals products that differ substantially in price and characteristics. Given the wide number of product choices and inherent challenges in interpreting ingredient lists for consumers, dermatologists may have to provide specific product and manufacturer recommendations to guide patients toward the most appropriate moisturizer."

Especially concerning, Silverberg said, is the practice of recommending moisturizers to patients with sensitive skin, underlying eczema, and other inflammatory skin conditions, where patients frequently apply topical agents to areas with an impaired skin barrier. "For these patients, I tend to recommend products that have a minimal ingredient profile to try to decrease the exposure that the patient will have long term," he said.

When a patient is allergic to one fragrance, the risk of having a reaction to other fragrances is much higher, because of the chemical similarity between ingredients, Silverberg explained. "We notice a comparable scenario with formaldehyde-releasing agents, whereby ingredients will degrade to the same chemical -- formaldehyde -- or there are enough chemical similarities to cause cross-reactions."

Consumers instinctively rely on product labels simply because they are visible, although not necessarily verifiable, he added. In fact, commercial claims for the moisturizers included in the study often did not fully reflect or even match the actual ingredient profile. "Several products contained well-established, classical fragrances in their ingredient list, yet the commercial label stated 'fragrance-free.' That is a complete disconnect. I am not sure how the claim of fragrance-free is justifiable in those products."

For moisturizers labeled as dermatologist-recommended, "there is no major requirement to substantiate that claim. It could be the recommendation of one dermatologist or it could be the recommendation of 100 dermatologists. Hence, it is not really a meaningful term, but rather a term that companies are allowed to use fairly liberally. As a dermatologist, I would not put too much stock into the claim."

Yet, Silverberg said, consumers are paying a premium price for moisturizers with claims of being dermatologist recommended, hypoallergenic, or fragrance-free.

The study found that the three most affordable moisturizers that were free of ingredients listed by NACDG were Ivory raw unrefined shea butter, Vaseline original petroleum jelly, and Smellgood African shea butter. "These are pretty safe and effective options for physicians to recommend to patients," he said.

A more complex issue is that some allergens may have dual purposes. "They may be used as preservatives as well as fragrances."

Recognizing the concept of cross-reactions is also important, he noted. "Outside the world of contact dermatitis, I do not think there is enough awareness about cross-reactions in the medical community, particularly within the dermatologic community."

For instance, a person can be allergic to one main ingredient as well as to other ingredients, "because there are enough chemical similarities between those ingredients. Fragrances are a classic example of this."

The most common potential allergens of 174 best-selling moisturizer products are the following, to analysis found:

1. Fragrance mix
2. Paraben mix
3. Tocopherol (DL-a-tocopherol)
4. Phenoxyethanol
5. Formaldehyde releasers
6. Propylene glycol
7. Benzyl alcohol
8. Iodopropynyl butylcarbamate
9. Cocamide diethanolamine
10. Methylisothiazolinone
11. Compositae mix
12. Lanolin
13. Lavandula angustifolia oil
14. Ethyl acrylate
15. Benzophenone-3
16. D-Limonene
17. Melaleuca alternifolia

The top 10 most reviewed products without ingredients listed by NACDG, according to the study:

1. Better Shea Butter unrefined shea butter
2. NOW Solutions sweet almond oil
3. NOW Solutions castor oil
4. Aveeno eczema therapy moisturizing cream
5. Molivera Organics ivory shea butter
6. Sky Organics organic shea butter
7. NOW Foods organic jojoba oil
8. Home Health castor oil
9. NOW Foods grape seed oil
10. NOW Foods avocado oil

This article originally appeared on the website of our partner , which is part of UBM Medica. (Free registration is required.)

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