The Role of Antihistamines in the Relief of Eczema Itching

Atopic Dermatitis is the genetic form of eczema and is the result of many different factors defects in the skin barrier; lipid (or fat) deficiency in the skin barrier, an overly alkaline pH of the skin barrier (partially due to a lack of certain fatty ACIDS in the skin), a susceptibility to bacteria and yeast overgrowth (probably due to the overly elevated pH), faulty cell cycling (at least partially due to disrupted calcium gradients in the skin), an increased rate of allergic reactions to certain chemicals that are applied to the skin, AND an overly exuberant inflammatory reaction (at least partially due to overgrowth of bacteria and to reactions to chemicals applied to the skin).  

Eczema is chronic in many cases, but can be prevented in those who are susceptible and very treatable in those who have it. Eczema most often affects children but is known to continue into adulthood.  In fact, a very large atopic dermatitis patient registry recently showed that approximately 50% of 20 year olds who had eczema as children still have it and are still treating it. 

Eczema has a number of symptoms however, relentless itching is one of the most irritating symptoms. Constant itching creates an uncontrollable urge to scratch the affected area.  Scratching provides relief only for a few seconds and repeated scratching can cause bleeding, oozing and worsening of the bacterial overgrowth by the Staph. aureus bacteria and possible infection.   

Finding a way to minimize the itch is important to anyone with eczema as is breaking the cycle of itch/scratch/itch. Moisturizing creams, topical ointments, and prescription steroid-type medications can help, provided you find the right one.  

Oral antihistamines, drowsy or non-drowsy, over-the-counter or prescription, are also known to help to break the cycle, especially during intense flare-ups. The effectiveness of antihistamines is the subject of controversy among medical professionals. 

What is an antihistamine? 

When the immune system is alerted to intrusive substances (allergens) it reacts to protect the body by releasing histamines into the blood. Histamines react further and cause allergy symptoms like runny nose, sneezing, or skin irritations.  Antihistamines "fight back" and give relief for many of the allergy symptoms. 

Do antihistamines help eczema? 

In the case of eczema, the symptoms manifest on the skin with itching being the most unbearable symptom of all. Some persons experience a high degree of itch relief after taking antihistamines, and some people do not find any benefit and do experience side effects such as drowsiness. 

Much research has been conducted to determine the effectiveness of antihistamines on eczema symptoms but there is no conclusive evidence that says that antihistamines affect the eczema itself.  The most exciting research in the area of antihistamines revolves around a few different histamine receptors in the body.  There are a few histamine receptors, but type 1, called H1, and type 4, called H4 receptor blockers have recently found to be very effective with both receptor types are blocked at the same time. 

There are no available H4 receptor blockers on the market as of yet, though many studies and trials are ongoing and are showing great promise in stopping the itch in eczema.  The mechanism appears to be due to inhibiting certain nerve growth factors and other inflammatory chemicals that drive the itch---this is a very exciting field and should yield some nice treatments for eczema sufferers in the future!

In the mean time, there are many H1 and H2 receptor blocking anti-histamines on the market.  In general, the only ones that are used for those who have eczema are intentionally used to sedate and to help one to sleep…..solely for the purpose of making you too drowsy to scratch yourself.  Sleeping through the night enables at least a few extra hours free from itching, and therefore, from scratching -- which in turn, helps break the itch/scratch/itch cycle. 

People who have these conditions (and others) typically should not take antihistamines: 

  • asthma, chronic bronchitis and other respiratory ailments 
  • high blood pressure 
  • glaucoma 
  • liver or kidney ailments 
  • chronic illnesses 
  • pregnant or breast-feeding women 

As with all medications, you should consult with your doctor to determine if and which antihistamine may or may not be best for you.  For the treatment of atopic dermatitis, one of the most commonly prescribed antihistamines is hydroxyzine (Atarax®) .  Diphenhydramine (Benadryl®)  is also very commonly used and both are quite sedating.  

Frankly, I have found limited benefit to the use of antihistamines in my practice.  I prefer to focus intensely on restoring  the skin barrier by addressing all of the all of the defective factors of the skin barrier simultaneously---and to avoid systemic medications when at all possible (probably 95% of the time).  This tactic has proven to be immensely effective and has helped many, many of my patients.