Featured Poison

Agave: And Then There was Tequila . . . and Dermatitis

Everyone has heard of tequila, or at least I hope you have. There’s nothing better than a margarita on the rocks while resting in the shade on a hot summer day . . . except two margaritas. Most people are too busy rimming a cocktail glass with salt to think about where tequila comes from, thankfully, that’s where I come in.

Tequila is a fermented product of the agave plant, specifically blue agave, Agave tequilana. The mecca for tequila production is the Mexican state of Jalisco, located on the southwestern coast of Mexico. By convention, at least 51% of the fermented sugars must come from agave, with the rest usually coming from cane sugar. “Silver” tequila must be distilled between 40% and 55% alcohol and is essentially the “pure” tequila. So what’s the “Gold” tequila? I naturally assumed the “gold” was better stuff since everyone knows that gold is worth more than silver. You “Go for the gold!”, not “Go for second place silver!” The “Gold” tequila is just silver tequila with caramel coloring. Seriously? Really. (1) Edit: Some high-end tequilas can be oak-aged, giving it a golden color. See comment by Milkshake, below.

Agave parryi by Justin Brower

Agave parryi by Justin Brower

The most likely origin of tequila comes from the ancient Ticuilas tribe that settled near modern day Tequila – which makes sense. Writings that pre-date the Spanish colonization/conquest/pillaging/genocide (your pick) makes reference to the locals cooking agave in water as a food source (1). What happened next is most likely how we obtained tequila, and most likely all of our fermented booze:

Some Ticuilan dude was too lazy to do the dishes and just left the agave water pot out one night. Day after day it sat there, taking in all of the local airborne yeasts. Weeks later, lazy dude went to find the pot again, and he found it still full of agave water. To hide his shame, and to keep from being called “The Lazy Dude” forever, pretended it was soup. “Mmmm, good soup,” he said. When in reality it tasted like tequila soaked gym socks. To get the horrid taste out of his mouth he poured salt on his tongue and ate some limes. “Hmmmm, not too bad,” he said, “I think I’m on to something.” His shame quickly turned to pride, which just as quickly turned to nausea, as he spent the next few hours praying to his porcelain gods. And that kids, is how tequila was born. At least that’s the bedtime story I told my girls, who have zero chance of turning out normal. Being a Dad is awesome!

Agave on the hike up Mt. San Antonio, with your's truly (circa 2003). For comparison, I'm 6'2

Agave on the hike up Mt. San Antonio (10,064′), with yours truly. For comparison, I’m 6’2″.

Returning to the agave plant, it takes between 8 and 12 years to become mature enough to be used to make tequila. And of the 300 or so agave species, only the blue agave has a high enough inulin (a fermentable polysaccharide) concentration, coupled with low fiber content, and other natural chemicals that contribute to the overall taste of the finished tequila product. Yes I used “natural” and “chemical” right next to each other, take that chemophobes.

But agave’s not all tequila shots and margaritas, that’s not enough to make it into Nature’s Poisons, there’s got to be something else. And there is: contact dermatitis.

We’ve seen contact dermatitis before with poison ivy and the manchineel tree, and now we’ve got another that goes by the moniker “mal de agaveros” – agave worker’s sickness. This is a common condition obtained by those that work in agave plantations and distilleries, though is most common in the distillery, with over 50% having experienced it. The primary location for this irritating dermatitis is on the forearm and neck for the distillery workers, and the abdomen for those in the plantation fields (2). The symptoms of  “mal de agaveros” is irritation, welts, and purpura – purple discolorations of the skin due to bleeding beneath the surface (3).

The cause of all this is the agave itself in the form of raphides. Raphides is a funny word, I’ll give you that, but there’s nothing funny about it. Raphides are calcium oxalate crystals that are sharp on one end and can grow from 100-400 nm in length, and serve as a mechanical defense akin to barbwire. There are 4000-6000 of these little buggers per milliliter of sap! But it’s not just the mechanical irritation from these miniature needles, once imbedded in the skin toxins from the agave nectar are free to enter the tissue and bloodstream, wreaking havok. The toxins most often associated with agave are saponins, steroidal glycosides (steroids with sugar molecules attached to it), similar to the solanines that we discussed in green spuds.

Raphides by Agong1 (public domain CC0)

Raphides, ouch, by Agong1 (public domain CC0)

So while you’re sipping on a margarita – and please, no watermelon, peach, hibiscus, or bacon margaritas – think of the workers who gave you their itchy skin so that you could imbibe in the nectar of the gods. On second thought, that sounds really gross, so I’ll leave you with a margarita recipe instead. Enjoy:

  • 2 ounces Silver Tequila (now that I know, no more caramel color added Gold for me)
  • 1 ounce Cointreau
  • 1 ounce lime juice
  • Shaken, not stirred, with ice, then poured into a salt rimmed glass over ice


1. Cedeño, Miguel C. “Tequila Production.” Critical Reviews in Biotechnology15.1 (1995): 1-11.
2. Salinas, Maria Lorenza, Tetsuya Ogura, and Luis Soffchi. “Irritant Contact Dermatitis Caused by Needle-like Calcium Oxalate Crystals, Raphides, Inamong Workers in Tequila Distilleries and Agave Plantations.” Contact Dermatitis 44.2 (2001): 94-96.
3. High, Whitney A. “Agave Contact Dermatitis.” Dermatitis (formerly American Journal of Contact Dermatitis) 14.04 (2003): 213-214.

4 thoughts on “Agave: And Then There was Tequila . . . and Dermatitis

  1. “Dorado” and “Oro” grades are colored with caramel, but “reposado” and “añejo” are aged in oak barrels for few months, they develop natural golden color.

    I guess margaritas from silver tequila make good sense (the finer tones being drown in lime juice), whereas “extra añejo” stuff is best drunk straight.

    • That’s good to know. Probably explains why the gold tequila in little tiny bottles is so expensive…maybe some day I’ll try the oaked styles.

  2. Thanks for the recipe, Justin. One Semina Santi weekend in San Philipe, Mexico, Leslie and I drank more than one or two of this delicious concotion. All other recipes are just pail imitations. Oh, as for your girls, they’ll turn out just fine.

    • Thanks, Dad. Yeah, margarita mixes from a bottle just don’t cut it. Fortunately we’ve got 3 blonde bartenders.

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