Over the past decade, there have been concerns regarding two aspects of parabens, firstly their estrogen mimicking properties founded in 1998, & a report by Darbe group in 2004 when 19 out of 20 breast tissue tumors contained traces of parabens. 

What we know is that parabens bind weakly to estrogen receptors, in the order of magnitude of around 1/4000 th capacity of estrogen itself, & that this experiment was in rats. In the context of breast cancer, there is no good evidence to suggest that there is a causative effect as no controls were conducted. At the time of writing (2022), there is no evidence that parabens are harmful in the context of malignant potential, this differs from sensation potential in higher risk individuals (even then it is low). 

It’s complex. There is undoubtedly a higher level of both irritant & allergic contact dermatitis in patients with sensitive skin including rosacea. The flipside is that the actual concentrations of parabens in makeup, cosmetics & prescription creams is low, somewhere between 0.3-0.4% at most. With this level, & irritant contact dermatitis is less likely to occur. Regardless it may seem sensible to use talc & paraben free make up, hence the marketing of mineral makeup. 

A reaction to any product in rosacea patients is more than likely irritant over allergic. If the latter is suspected, a medical dermatologist with an interest in allergic contact dermatitis can test you for the standard battery of allergens & your own cosmetic series. 

Parabens are harmful or potentially problematic if there are open wounds, most commonly chronic ulcers. This includes venous, arterial & diabetic ulceration. In this situation the skin’s barrier function is compromised. On this basis dermatologists, vascular surgeons, & wound care nurses may avoid parabens. Patch testing is useful if allergic contact dermatitis is suspected.

From a marketing perspective, having a paraben free product may be important to keep up with other natural/organic products & green skincare (green is probably the same colour of the creams as they have been infected with pseudomonas). Though it has no scientific evidence, I can understand why companies opt for this buzzword. 

Extremely low. You have infinitely higher chances of developing allergic reactions from other preservatives including formaldehyde & quaternium-15 & even higher reactions from fragrances & nickel. As a reference tea tree oil has a higher rate of reactions following patch testing, namely 0.6 to 3.5% as compared to around 0.6% for parabens.

Remember this percentage is for patients attending patch testing clinics, & not the general population, this is much lower. An increased rate of ACD is seen if the barrier is compromised, namely chronic ulceration. 

Medical dermatologists perform what is known as patch testing. Essentially they test a mix of parabens consisting of methyl, ethyl, butyl & propyl paraben in a 15% concentration (this is over 20 times more potent than the concentration found in skin care products, typically 0.4% to 0.8%). If you have sensitive skin, there may be a crossover with irritant dermatitis.

Patch tests are read over one week by either the dermatologist themselves or their nurse. If a reaction is present, interpretation is super important.

Here is the irony of it all. Other preservatives are much more problematic than parabens. In fact the rate of true allergy is in the order of 0.6%. This is so frigging low that the patch test society of dermatologists have labeled parabens as the non-sensitizer of the year some three years ago. For context the chances of allergic reactions (in individuals who attend a patch test clinic, not in the general population) is as follows; 

• Formaldehyde: 9% 
• Quaternium-15: 9%
• Diazolidinyl urea: 2.7-3.7%

So, are there certain people who should avoid parabens– excluding those who have done their own research & have made up their mind as to the estrogenic or carcinogenic effects of this preservative? Yes, these groups include-

• History of type 4 allergic contact dermatitis to parabens based upon patch testing with either the European standard battery or ROAT under the supervision of a dermatologist.
• Patients with a high sensitization potential including chronic ulcers & rosacea (controversial)

Your dermatologist will give you a long list of products to check against including topical prescription medications, toothpaste, sunscreens, cleansers, moisturizers as well as polish, lipstick, make up & more. Cross reactions with PABA or para-amino-benzoic esters & paraphenylenediamine or PPD do occur.

Yes, in theory but in actual fact this is rare. Food that is rich in parabens include; 

• Marinated fish products
• Mustard, mayo, salad dressing, sauce
• Processed vegetables
• Frozen dairy products
• Jams and jellies
• Soft drinks and fruit juices
• Baked goods and candies

In some cases a ROAT test or repeat open application test can be useful, especially if you think a product may be responsible for your reaction. Apply a small amount of product twice a day to your inner forearm for 5 to 6 days. If it reacts it may be paraben (or one of the other dozens of things).  It does not work for shampoo as an irritant reaction is more common. Ideally you should see a dermatologist with an interest in contact dermatitis & patch testing as interpretation can be tricky. 

Lots, it is complex, I used to know most of these for the exams. Here is a list; 

• Methylparaben
• Ethylparaben
• Propylparaben
• Butylparaben
• Benzyl-parahydroxybenzoate 
• Methyl-parahydroxybenzoate 
• Ethyl-parahydroxybenzoate (p-hydroxybenzoate)
• Propyl-parahydroxybenzoate (p-hydroxybenzoate)
• Butyl-parahydroxybenzoate (p-hydroxybenzoate)
• Parahydroxybenzoate