Why Do Bug Bites ITCH?
An Intro to ITCHING
Itching, according to one medical definition penned over 300 years ago, may be defined as "an unpleasant cutaneous sensation which provokes the desire to scratch." Not a bad definition as far as definitions go, in my opinion.
However we choose to define it, itching from insect bites and stings is ANNOYING.
But why do these bites from insects like mosquitoes, flies, spiders and bees cause itching?
That is the question I hope to answer for you. The answer will also help us to think about the most appropriate treatments and remedies for itchy bug bites.
The physiology of "itching" (medically known as "pruritis") is more complex than we might at first expect. Many mechanisms and pathways have been proposed. In this article I do not intend to plunge into the highly technical debates regarding these various models. I am going to explain the most well recognized and (in my opinion) most likely explanation for the majority of insect bite reactions: the Histamine Response.
By the way, we all know that bug bites are not the only thing that causes itching. Some other common culprits include:
- Dry skin
- Skin infections
- Stress & Anxiety
- Plants (like poison ivy or oak)
Histamine & the Immune Response
Too late. He bit you. Well, to be more correct, I should say "SHE" bit you, as the biting mosquitoes are all female.
When blood-sucking insects, like mosquitoes, bite (actually, they have no teeth, so "pokes" or "stabs" is more appropriate) they secret a small amount of saliva into our skin.
This saliva is quickly identified as FOREIGN by our body. As a result, an IMMUNE SYSTEM response is immediately triggered. Part of this immune response involves the release of a substance known as HISTAMINE from certain cells known as Mast Cells.
HISTAMINE HISTORY: Histamine is your friend...usually. It is a little organic molecule which rests happily inside many cells in your body, particularly Mast Cells. When Mast Cells recognize a foreign invader (they are pretty good at that) they sound the alarm..by releasing (amongst other things) Histamine!
Histamine then heads toward anyone that will listen to it talk. Specifically, a "receptor" that is trained to listen to histamine. We give these receptors fancy names like H1, H2, H3, etc. Real clever, huh?
Anyway, it is specifically when Histamine talks to receptor H1 that the ITCHING begins. It is also when Histamine talks to H1 that things like vasodilation (causing hives) and even motion sickness occur.
Think of itching like a LOUD conversation going on between HISTAMINE and the H1 receptors. Yack, Yack, Yack...they just keep on talking and blabbing as long as the irritating saliva from the insect is still hanging around. Eventually, it goes away. The conversation moves from yelling, to talking, to whispering...to quiet once again. Itching over.
Treating Itching from Insect Bites
Scratching, though it may feel good, is not the best approach to treating the itch. Not only is it distracting, but it can lead to broken skin, pain and infection. Not good.
But since we now know WHY (in some measure) bug bites itch, we can attempt a solution at solving this problem.
Remember, using our illustration, itching is like a LOUD conversation going on between Histamine and the H1 receptor. A sort of "shouting match" if you will.
How do you silence a shout?
3 Pharmaceutical Approaches to stopping itching:
TREATMENT 1: ANTIHISTAMINES: An antihistamine is a product that "silences" the shout going on between Histamine and the H1 receptor. It is, if you will, like a "chemical duct tape" over the mouth of these noisy molecules. Many choices of antihistamines are available over-the-counter such as topical Benadryl or oral products like Claritin, Allegra, Zyrtec or oral Benadryl. Always check with your doctor or pharmacist to make sure you can use one of these oral products safely.
TREATMENT 2: TOPICAL STEROIDS: Topical steroid creams, like hydrocortisone, help alleviate itching by exerting an anti-inflammatory effect. Think of steroids "dispersing the crowd" around the loud and angry Histamine and H1 receptor shouting match. A small amount of hydrocortisone cream applied once or twice daily often helps relieve itching. Stronger steroids are available by prescription for more severe cases.
TREATMENT 3: DISTRACTION PRODUCTS: Virtually every other product used to treat itching from bug bites works by "distracting" our mind from the itching sensation going on below. Sort of like turning up the radio to block out the noise of the screaming children. It works, and by the time you turn the radio back down (hopefully) the little angels have yelled their lungs out and are playing quietly again. Distractions products tend to contain ingredients like camphor or menthol or rubbing alcohol. This phenomena is, by the way, the secret behind most "home remedies" for itching also, like baking soda, oatmeal, lemon juice, cold compresses or mint.