Taking the Itch Out of Summer

I came back from our last vacation somewhat miserable. The mosquitos and black flies had made a meal of us, despite wearing bug nets, long sleeves, and pants. While mosquito bites typically disappear for me after a day, it seems black fly bites are a lot worse. My husband had about 28 black fly bites across the back of his neck and around to his cheek. Not to be outdone, I had no less than 50 bites across my lower back, with bonus bites on the back of my ankle and finger. The black fly bites took longer to swell up, but once they did, oh boy were they itchy. And mine were constantly rubbing on the back of the seat and footrest at home, which made them swell up even more. An interesting fact: Just like with mosquitos, only female black flies bite. So those blood-sucking fiends are exclusively female. How nice.

I remembered that After Bite’s active ingredient is ammonia and started wondering if there may be a potential remedy there. I like using single ingredients that take advantage of the properties of active ingredients in commercial products without having to worry about a possible reaction to the inactive ingredients. Plus, ammonia is cheap. I can buy a litre of household ammonia for $5 to $10, whereas 14 mL of After Bite would cost me $9.35, or approximately $668 per litre. That’s a big difference in price just to buy a product with more inactive ingredients.

I put up with the bites for a whole day after returning home, during which the swelling and itching got even worse, and then pulled out the ammonia to try it. I mixed up a solution of ammonia and water and applied with a cotton swab. Within 10 minutes of applying the ammonia solution, the itch was gone, never to return. Within 24 hours of applying the ammonia solution, the swelling had decreased considerably.

What’s actually in After Bite and does it work?

Since returning home, I’ve learned that there are several formulations of After Bite, containing various proportions of ammonia, baking soda (sodium bicarbonate), and tea tree oil. Some are more effective on certain types of bite than others, but the most recommended version does indeed contain ammonia. I would never suggest applying essential oils to allergic skin (see my post about Essential Oil), so I’m not even going to discuss the tea tree oil. But baking soda and ammonia have promise. I know a baking soda paste has been a home mosquito bite remedy for years. I’ve never had much luck with it, but it’s certainly a very safe remedy to try.

What really intrigued me was the ammonia. It turns out that there is a reasonably valid scientific study showing the effectiveness of ammonium on mosquito bite itch relief here. Ammonium and ammonia are not quite the same chemical – ammonium is an ion formed from ammonia when the ammonia molecule gains one extra hydrogen atom. Ammonia reacts with water to form ammonium and hydroxide ions. If After Bite says it contains ammonia and water, it actually contains ammonium. So we are essentially talking about the same thing when discussing ammonia and ammonium in this context. No issue there.

Based on the study, ammonia really does cure the itch. But why?

A brief internet search does not yield a whole lot of quotable evidence but suggests that bugs (mosquito for example) may be injecting formic acid into your skin. Baking soda is an alkali, and ammonia is a stronger alkali. The alkalinity may neutralize the formic acid, and thus the itch and irritation. In my own tests, the itch removal from ammonia was permanent, and the reduction in swelling was obvious, which supports the hypothesis that there is something being neutralized. I wish I could provide more to support this, but unfortunately, I can’t find anything else at this time.

How do you use it?

After Bite contains 3.5% ammonia. That’s equivalent to 7 parts ammonia in 13 parts water. I do not know the concentration of ammonia in each individual ammonia solution bottle, so I can’t provide you with a concrete formula to mix that up. I don’t even know the concentration of ammonia in my own ammonia bottle. What I can say is that I have successfully used my specific bottle of household liquid ammonia diluted to 70% strength in water (7 drops of ammonia and 3 drops of water). I applied with a Q-tip and rinsed the remaining solution down the drain with water, rinsing the Q-tip off and putting it in the garbage. I had no irritation. Some websites say to use household ammonia neat. I cannot vouch for this because I have not tried it.


Use caution. There’s a warning label on the bottle of ammonia for a reason. Ammonia is corrosive, and can cause chemical burns to the mouth, throat, stomach, and eyes. Skin contact with concentrated ammonia can cause irritation and burns. This is why I used a dropper to mix only a small amount of solution, and used household ammonia solution, not industrial solution, which is much stronger. Ammonia fumes are also corrosive. If ammonia is mixed with other cleaning chemicals it can create a toxic gas. That said, ammonia is also one of the main active ingredients in Windex and some other household cleaning products, so it is possible to safely use it, just exercise care when using. Read more about ammonia here

The next time you’re outside or out camping and get an itchy bug bite, consider pulling out the household ammonia. You may be very pleasantly surprised.

If you don’t want to try ammonia – but trust me and the science, it works – the internet suggests several other itch remedies you can apply (topically) to your bug bites. I’m not going to go into if they work or why, but they should be harmless enough to try. Do not use any of these if you are allergic to them or any of their components:

  • An ice cube or ice pack (5 minutes or less at a time, or a bit longer if you use a towel between your skin and the ice)
  • Aloe Vera
  • Aspirin, crushed, made into a paste with water
  • A lemon or lime slice
  • Honey
  • Baking soda mixed into a paste with water
  • Oatmeal mixed into a paste with water
  • Vinegar
  • A cut onion or crushed garlic
  • Witch hazel

Have a safe and itch-free summer!

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