Tonic water contains quinine as its active, bittering ingredient. Quinine comes from cinchona tree bark. Homemade tonic waters begin with this tree bark either in chunk or powdered form. The powdered form is particularly hard to strain out of the final beverage, and this could lead to an accidental overdose.
The symptons of cinchonism (from wikipedia):
Symptoms of mild cinchonism (which may occur from standard therapeutic doses of quinine) include flushed and sweaty skin, ringing of the ears (tinnitus), blurred vision, impaired hearing, confusion, reversible high-frequency hearing loss, headache, abdominal pain, rashes, drug-induced lichenoid reaction (lichenoid photosensitivity), vertigo, dizziness, dysphoria, nausea, vomiting and diarrhea.
A scientific paper published in 2007 reported a case of a patient self-medicating for leg cramps with quinine and it turns out he gave himself cinchonism. His systems were intermittent fevers, chills, and tremors for approximately 12 days; general malaise that would begin with a bitter taste in his mouth that wouldn't go away. (On PubMed the article is at PMID: 18004031)
Glasser wrote about his incident on his Facebook page, and I asked if I could reprint it. The Glassers are the founders of Bittermens, makers of bitters, spirits, liqueurs, and other products. Thus they are very familiar with quinine. He wrote:
How did it happen? Well, we work with cinchona all of the time, which means that our bodies already have a small buildup of quinine. During Tales of the Cocktail, we had a gin and tonic at a restaurant where they made their own tonic syrup. By the amount of the suspended cinchona dust floating in the drink and the distinctive earthy tannins that mark incomplete filtration, we should have stopped drinking it at the first sip. But we didn't, and spent the next two days dealing with the very uncomfortable symptoms of cinchonism.
Safe Amounts of Quinine in Tonic Water
The below information all comes from Avery Glasser.
There's a federal standard for the use of quinine in carbonated beverages, specifically that it cannot exceed 83 parts per million in the final tonic water (21 CFR 172.575). Now, if you're working with commercial quinine sulphate or quinine hydrochloride, it's easy to calculate. Basically, that ends up being 2.48 mg of commercial quinine per ounce of tonic water.
So, let's expand this out: a typical gin and tonic is 1.5 oz of gin and 4.5 oz of tonic, 6 ounces total. That means we can expect 11.16mg of quinine in that beverage.
However, most producers of tonic syrups don't use quinine hydrochloride/quinine sulphate... and there's the rub.
Cinchona bark is approximately 5% quinine.
The Most Popular Tonic Water Syrup Recipe Has Too Much Quinine
Let's take one of the most popular tonic syrup recipes, published by Jeffrey Morgenthaler: Basically, it's 6 cups of liquid to 1/4 cup of powdered cinchona bark, which is about 35 grams of cinchona. Extrapolate from that and we're talking about 35 grams of cinchona per 1.4 liters of end syrup, which is 25 grams per liter, and if it extracts fully, contributes 1.25 grams of quinine per liter, which equates to 1251 parts per million. That's 15 times the CFR standard.
If you use 3/4 of an ounce of that syrup in a Gin and Tonic, you're adding in 27.5 mg of quinine - more than double the amount of quinine in a commercial gin and tonic.
Note: Does a syrup extract quinine fully from the cinchona? No - but it extracts faster from powdered cinchona versus cinchona chips or quills.
Note: Does a syrup that is sieved through a french press or a coffee filter have a high percentage of solids still in suspension? Yes - and any of the solids you swallow contribute the full amount of the quinine as your body digests the powder.
Quinine in Bittermens Bitters and Liqueurs
Glaslser says, "We work with small amounts of cinchona in many of our bitters. At our concentration, there's only about 1.1 grams of cinchona per liter in the maceration, and all of the solids are removed down to 5 microns, which means there's barely any cinchona left in the mix. If we say that we get a full extraction of quinine from the cinchona before we filter it out, then we're talking about contributing about 57 mg of quinine per liter of bitters, or assuming a half ml of bitters per cocktail, we add no more than 0.0283 mg of quinine to a cocktail, or raise the total amount of quinine by 0.19 parts per million. Again, that's assuming that we left all of the cinchona bark in the final product, which we do not as we don't use powdered cinchona (we use larger pieces of bark). Most likely, we're contributing less than a tenth of that amount.
Avery Glasser's Conclusion
All I'm saying this this: be careful. Bitters and tonic syrups can be fun to make, but they can be dangerous if you don't know what you're doing. I'm not saying that you need to be a food scientist or a compounding pharmacist to do things safely, but you have to understand that you're working with potentially harmful substances! Indian Calamus root, Virginia Snakeroot or tobacco - even in small amounts can have horrible and irreversible effects. Just last week, I was told about a bar that was soaking stone fruit pits in neutral grain and had no idea about cyanide toxicity.
For us, it's now five days later and the symptoms are basically gone, but it also means we have to be careful about having cinchona for another week or so.
That's it. No rant. Just a plea for my health and the health of all of our friends and customers: think carefully before making your own tinctures, extracts, bitters and syrups.
Based on the above information, the following recommendations seem prudent. These are from me.
- If you're using powdered cinchona tree bark, try extra hard to strain it thoroughly. I've strained it through 2-3 coffee filters (I run vodka through the coffee machine to do my extractions with quinine powder in the basket) and there is still a quantity of the bark solids that pass through the filters. In the future I might strain it more.
- Filter your bark before you add sugar or you'll gum up your filters.
- If you are testing recipes with homemade tonic, keep your samples small.
- As Glasser experienced, quinine/cinchona can build up in your system. So go easy on the intensive homemade tonic syrup drinking, and beware of other tonic syrups with lots of barky bits.
Thanks to Avery Glasser for sharing his story - and the math - with us.