In the previous post on itchy skin, we discussed the data on the prevalence of itch and the lack of satisfactory itch treatments. Here, we take a deeper dive into available itch treatments and their efficacy and safety.

Topical Antihistamines

There are more than 70 distinct chemicals that are believed to mediate itch symptoms. Histamine is the most well-known of these itch and inflammation-triggering chemicals. Histamine binds to the type C nerve receptors and triggers the brain to produce an itch sensation, so antihistimines block the histamine from binding to the receptors.

A risk associated with using topical antihistamines is triggering a secondary allergic reaction identical to that experienced with poison ivy. Another common side effect of antihistimines is drowsiness.

Notwithstanding, the lack of effectiveness of topical antihistamines and their safety concerns, topical antihistamines like Benadryl™ continue to be widely sold and, presumably due to their placebo effect, consumers continue to purchase them.

Topical Local Anesthetics

Topical anesthetics are a common treatment for itch, and they essentially act as numbing agents to quiet itch symptoms in an affected area. Active ingredients like benzocaine and lidocaine are commonly used in over-the-counter products. However, benzocaine is one of the most likely ingredients to cause a secondary allergic reaction identical to that experienced with poison ivy/oak/sumac. It’s estimated that 1% of benzocaine users may experience this.

Another concern with topical anesthetics is the potential for systemic absorption. Although an unlikely occurrence when used as directed, applying topical anesthetics to large areas of the body repeatedly poses a danger of systemic toxicity, essentially drug overdose.

Risks:

• Secondary allergic reaction identical to poison ivy, oak, or sumac
• Systemic absorption
• Numbing and loss of function
• Short duration of relief, only 15 to 45 minutes[1]

Glucocorticoids (i.e., Cortizone-10)

Working on reducing the inflammation that can cause itch, these products have no direct effect on the sensory irritation, i.e., the itching, burning and stinging sensations. So they don’t work right away, they take a day or more to produce any significant benefit, and since they don’t target the itch nerves directly, they are ineffective on many common itch conditions, such as acute contact dermatitis – like poison ivy, jewelry allergies, bug bites and atopic dermatitis.

Risks:

• Thin skin
• Discoloration
• Redness
• Bruising easily
• Stretch marks

Topical Counterirritants

These products, with ingredients such as menthol and camphor, provide no direct itch relief. Rather, they activate other nerve subsets that send a cold or “cooling” sensation to the brain, thus distracting you from the itch. They have limited effect and last only for a limited time.

[1] American Pharmaceutical Association’s Handbook of Nonprescription Drugs

Why do we still suffer from itchy skin?

Itch. It’s something I’d venture to say we’ve all experienced. When surveyed, 78% of adults reported experiencing some type of itch or skin irritation within the past year.[1] Itch, in particular, can range from as mild and temporary as a mosquito bite to as severe and chronic as psoriasis. In fact …

“… although itching is popularly perceived as a minor social or even humorous disability, it is frequently so severe and intractable as to cause the sufferer abject misery or even suicidal inclination.”

– Fitzpatrick’s Dermatology in General Medicine

Can you imagine having itch so severe you can’t sleep, think, or even function? Unfortunately for some this is a daily reality. But for most of us, itch is just an occasional annoyance. And about 49% of us head to the drugstore for a solution.[2]

Considering there are multiple triggers for itch, it is surprising how lacking the offerings are in terms of effective itch treatments. Consider this: The need for new and improved itch treatments was famously demonstrated in a 1964 study where 12 patients were treated with four different oral anti-itch medications in rotation so that each of them received each treatment during the study. The most effective treatments were 66% effective in relieving itch symptoms! And only 16% of treatments produced side effects like nervousness or grogginess, not bad. BUT here’s the catch … all the treatments were placebos!

So that means a placebo performs as well as, if not better than, many medications at relieving itch. Fitzpatrick’s Dermatology in General Medicine authors state,

“as of 1998, no specific anti-itch drug of proven efficacy was available.”

Even in 2003, leading itch scientists stated, “Currently there are no satisfactory selective anti-itch treatments.”[3]

And when it comes to over-the-counter remedies, in a 2012 Harris survey, more than one in three people surveyed said they were not satisfied with OTC options available to treat itch.[4]

Here’s a quick breakdown of what happens when your skin itches. Your skin has two types of itch nerve receptors, A-Delta nerves that produce the sharp, pricking pain of a needle, and type C nerves that cause itching, burning, stinging sensations and inflammation. Irritants such as chemicals, allergens or insect bites easily activate type C nerves. When the itch stimulus enters the skin, type C nerves send an itch signal to the brain and trigger the body to release histamine that dilates the blood vessels, causing redness and swelling.

In the next post, we’ll cover common topical anti-itch treatments and their relative efficacy and safety.

[1] 2012 Mintel Medicated Skincare Report
[2] Ibid.
[3] Itch Associated with Skin Disease: Advances in Pathophysiology and Emerging Therapies.
[4] 2012 Harris Interactive online survey of 2,213 U.S. adults aged 18+