What Do Smelling Salts Smell Like

“I have a friend who is obsessed with smelling salts and has been trying to make his own at home since he was 10 years old. He’s made several batches over the last decade and I’ve seen him try out different recipes in search of the perfect one. His latest concoction involved mixing together baking soda, vinegar, and water until it bubbled up into a foamy mess that smelled like sour milk.
He swabbed his face with it thinking this would help revive him during an asthma attack. It didn’t work because, well, most people don’t know what smelling salts smell like. They’re not just some cheap gag gift you can buy from your local toy store or drugstore. Most people think they’ll smell vaguely medicinal — maybe like rubbing alcohol or something — but when you open the box and break off a little bit of salt and dump it on your wrist, all you’ll get is a strong ammonia fart.
Smelling salts were traditionally used by doctors and nurses (or “”nurse practitioners””) before modern anesthesia came along in the early 19th century. When someone had trouble breathing, these healers would give them smelling salts so their nostrils could expand and take in more oxygen. The idea behind them was based upon the theory that sickness and disease was caused by bad air moving through our bodies. If the air inside us smelled good, then we’d feel better about ourselves and live longer.
The first known recipe for smelling salts dates back to 1657 and was written by Dr. William Harvey. It called for combining two parts of lye with three parts of distilled water until boiling point, adding nine ounces of camphor oil, stirring it around, and putting it into jars. This mixture supposedly gave off a scent similar to incense. In 1826, Dr. Benjamin Rush wrote that “”the fumes of Camphor”” helped treat patients’ pain. And it wasn’t until 1840 that Dr. John Hesselius suggested using ammonia instead of camphor oil.
In 1870, a Massachusetts physician named James E. Keene created the original patent medicine version of smelling salts. These packets contained boric acid, potassium sulfide, sodium carbonate, and other ingredients. You dumped a small amount onto your wrists, inhaled the fumes, and voila! Instant feeling-good vibes.
Today, there are multiple versions of the stuff sold online and at stores like CVS, Walgreens, Dollar Tree, Target, etc. But even though the packaging may look fancy and say things like “”Pure Potassium Sulfite,”” the actual substance in each product will be identical. That’s right; every single one contains ammonium hydroxide.
So how does this chemical compound produce such a powerful aroma? Well, if you’re familiar with pH levels, you might already understand why ammonium carbonate smells like ammonia. Its pKa is 9.2. So basically, the higher the number, the less acidic something becomes. For example, water (pH = 7) is very slightly acidic while urine (pH = 5) is extremely acidic.
Ammonia itself doesn’t have a particularly distinctive odor. However, when mixed with carbonic acid (which makes up part of baking soda), hydrogen gas, and another ingredient, it produces a distinct ammonia scent that’s similar to rotten eggs.
This process happens thanks to a reaction between those four elements:
NH4 + CO3OH -> NH3 + HCO3
When you mix baking soda and vinegar together, the resulting fizzing reaction looks like this:
NH4 + CH3COOH -> NH3 + CH3COOCH3
Here’s where smelling salts get fun. Instead of letting the reaction run rampant, chemists add a catalyst — usually an alkali metal like lithium, sodium, magnesium, or calcium — to speed up the process. Then they heat the solution up to 100 degrees Celsius (212 degrees Fahrenheit). At this temperature, the ammonium carbonate dissolves into the liquid, creating large bubbles filled with ammonia.
Since the molecules are so tiny, they move freely throughout the liquid without bumping into anything. Once they reach the surface, they release the trapped nitrogen gas. Because the compounds are so volatile, the ammonia vaporizes quickly and floats away. As soon as you breathe it in, it goes straight to your brain, where it binds to receptors near your olfactory nerves. There, it stimulates nerve endings that send signals to your spinal cord and brain telling it to relax, reduce muscle tension, lower heart rate, increase appetite, and make you happy.
For anyone who’s ever felt anxious or depressed after eating a meal, this probably sounds pretty darn awesome. Unfortunately, no matter how much you want to believe otherwise, smelling salts aren’t actually a magical cure-all. While smelling salts do seem to relieve headaches and nausea, they’re not recommended for treating serious medical conditions. Plus, taking them too often can cause skin rashes and respiratory problems, according to the American Association of Poison Control Centers.
If you do decide to use them, here’s a quick primer on how to administer them properly.
How to Take Smelling Salts
It’s important to note that smelling salts should never be taken internally. They shouldn’t be given to children under age 12 and definitely not to pregnant women or nursing mothers.
Instead, follow the instructions on the label. Some products will tell you to put a pinch of the powder directly on your nose, while others recommend wetting your wrist and holding your arm high above your head.
Either way, the key is to wait at least 30 seconds before doing something else. Afterward, wash your mouth with warm water and spit it out. Don’t rinse.
And remember, it’s always best to seek medical attention if you experience any adverse effects. Just because you took smelling salts once doesn’t mean you should start popping them whenever you find yourself struggling to catch your breath. ”