Updated: Jul 28, 2019
As the summer comes around, I get asked a lot in the pharmacy: “What can I use for a mosquito bite?”
You can google a lot of treatments, and you will probably get many products. Which is the best? My opinion on this is: ‘it depends on the timing’.
A mosquito penetrates the skin using a needle like “proboscis” . The mosquito injects some saliva into the wound, to numb and anti-coagulate the blood in the area. This will make the puncture less painful, and prevent the blood from clotting to allow the mosquito to draw blood from the blood vessel beneath the skin.
Itching and swelling occurs because your body has an allergic reaction to the proteins in the saliva of the mosquito. It is especially bad because the saliva is injected under the skin and cannot be reasonably washed out.
Knowing this, what is the best way to treat a mosquito bite? The easiest, and most obvious was is to treat the swelling. Creams such as benadryl cream or 0.5% or 1% hydrocortisone cream will help with the swelling and itching. Antihistamine tablets will help if the bites are all over your body. I tend to recommend Benadryl tablets, or Cetirizine (Reactine) (see: Karpinen et al, 2002).
Another way is to stop the itching and swelling very quickly is to actually break down the protein in the saliva before a significant allergic reaction occurs. How can this be done?
The answer is Ammonia (NH3) ...and maybe Baking Soda (NaH2CO3). Ammonia is a ‘basic’ compound (a pH higher than 7). Because of Ammonia’s basic characteristic, it will break down proteins that it comes into contact with, including the proteins within the saliva. A study conducted in 1998 (Zhai, Packman, Miach, 1998), showed this. Baking soda however….doesn’t really have concrete data behind it, but I think it will have the same mechanism, because anecdotally it works on bites. The one product that I know carries Ammonia, is After-bite, it also happens to carry Baking soda as well.
Knowing this, what I recommend is:
If the bite is very fresh, use After-bite. The after-bite will hopefully travel down the mosquito bite under the skin and break down the saliva. This will stop the bite from getting itchy and swelling or at least reduce the itchiness. If your body is covered in bites, then take an antihistamine tablet, because you probably don’t want to lather yourself in after-bite.
However if it has been several hours after the bite, after-bite will lose its effectiveness because the bite will have closed up due to swelling, and the after-bite cannot get to the right area. At this point, I would recommend either creams, or antihistamine tablets for temporary relief.
In short, treat the bite fast with after-bite, or if you did not notice the bite and it’s several hours later, treat with creams or anti-histamine tablets. For this reason, always carry after-bite. If you just killed a mosquito, put after-bite on the bite right away.
What is your experience with treating Mosquito bites? Do you have a personal remedy? What alternative treatments have you heard about?
Karppinine, A., Kautiainen,H., Petman,L., Burri,P., Reunala,T. (2002). Comparision of Cetrizine, Ebastine, and Loratadine in the Treatment of Immediate Mosquito-bite allergy. 57(6), 534-7.
Zhai, H., Packmn, E.W., Maibach, H.I. (1998) Effectiveness of ammonium solution in relieving type I mosquito bite symptoms: A double-blind, placebo-controlled study. Acta Derm Venerologica, 78(4), 297-298.