If you’re the type who loves a culinary challenge—whether it’s a fiery vindaloo, a tongue-tingling wasabi hit, or a mouth-puckering lemon tart—then you might want to brace yourself for the latest sensation sweeping the sweet tooth scene.

This isn’t your average lolly from the corner shop. No, this is a confection so sour, so intense, that it’s been dubbed the ‘world’s sourest sweet’—and it’s causing quite a stir online and in sweet shops across the UK.


Created by English confectionery company Mr Simms, the Black Death sweet is a jet-black, lemon-flavoured boiled lolly dusted with a thick layer of acid crystals.

It’s not just a treat; it’s an endurance test. Mr Simms claims it’s the sourest sweet on the planet, out-souring even the likes of Sour Patch Kids, Toxic Waste, and Warheads.


And with a warning label that says it’s not suitable for anyone under 12, you know you’re in for a wild ride.

The sweets are available exclusively at Mr Simms’ ‘Olde Sweet Shoppe’ stores in the UK, with prices ranging from £4.50 (A$9.4) for 200g to a whopping £21.79 (A$45.5) for a whole kilo.

But before you rush to order a bag for your next family gathering, be warned: these aren’t your garden-variety lollies.


The secret to Black Death’s mouth-puckering power lies in its ingredients. Alongside the usual suspects—sugar and glucose syrup—you’ll find malic acid (the same compound that gives rhubarb and green apples their tartness) and citric acid (familiar to anyone who’s ever sucked on a lemon wedge).

There’s also black iron oxide, which gives the sweet its dramatic charcoal colour, and a generous dusting of acid crystals on the outside.

While citric acid is a common food additive (and even used as a de-scaler in cleaning products!), it’s perfectly safe in small amounts.

But when concentrated on a lolly, it can deliver a shock to the taste buds—and, as some have discovered, even irritate if you overindulge.

Curious to see if the Black Death lives up to the hype, I steeled myself for a taste test.

The first thing you notice is the warning on the packet: 'Not suitable for children under 12 years of age. CAUTION: Excessive consumption within a brief time frame may cause temporary mouth and/or stomach irritation.'

Not exactly reassuring, but I pressed on.

At first, the sweet seems innocent enough—just a hint of tang.

But within seconds, the sourness hits like a freight train. Imagine biting into a grapefruit, peel and all, or sucking on a lemon with a side of battery acid.

My face contorted, my eyes watered, and my mouth puckered in protest. It’s easily the sourest sweet I’ve ever tasted, and for a moment, I understood why some people have to spit it out immediately.

But here’s the twist: after about 20-30 seconds, the intensity fades, and the sweet transforms into a pleasant, fruity lolly.

The initial shock is all thanks to the crusty acid crystals on the outside—once you’ve powered through them, the rest is a breeze.

There’s even a final burst of sourness at the centre, but it’s nothing compared to the opening salvo.

While the Black Death sweet is a fun novelty for adults and older kids, it’s not for everyone.

There have been reports of children experiencing mouthburns and even hospital visits after trying ultra-sour lollies like these.

Scientists warn that too much acid can damage the delicate skin inside your mouth, so moderation is key.

If you’re game to try it, start with just one, and don’t leave them lying around for little ones to find.

And if you have sensitive teeth or a history of mouth ulcers, you might want to give this one a miss.

All in all, the Black Death Sweet is a wild ride for your taste buds—a must-try for anyone who loves a food challenge but not for the faint-hearted.

It’s a great party trick, a conversation starter, and a reminder that sometimes, the most memorable treats are the ones that make you wince!
Have you braved the Black Death, or do you have a favourite sour lolly from your childhood? Maybe you’ve got a story about a food challenge gone wrong (or right!). Share your experiences in the comments below.