Chaga in Ireland: What It Is, the Real Evidence, and Important Safety Points

By the cosc.ie team · Updated 7 October 2026

Chaga has become a popular ingredient in "mushroom coffees", teas and tinctures in Ireland. It has a striking look, a long folk history in northern Europe and Russia, and plenty of bold claims online. This guide sets out what chaga actually is, how little human research there is, the safety points that matter most, and what to look for if you decide to try it.

What is chaga?

Chaga (Inonotus obliquus) isn't a typical mushroom at all. What people harvest is a hard, black, cracked growth called a sclerotium, which looks like burnt charcoal on the outside and is rusty orange inside. It grows mainly on birch trees in cold northern regions: Scandinavia, Russia, the Baltic states, Canada and the northern United States. It is rare in Ireland.

In parts of Russia and Scandinavia, chaga has been brewed as a tea for centuries. It has a mild, earthy, slightly vanilla-like taste, which is why it works well in coffee alternatives.

Wild-harvested vs cultivated

Most chaga on the market is wild-harvested. That raises two concerns:

• Sustainability: chaga grows slowly, often over many years, and demand has led to over-harvesting in some regions. Responsible harvesters take only part of the growth and leave the rest to regrow.
• Consistency and contaminants: wild material varies in quality and can pick up contaminants from its environment, so testing matters.

Some products use chaga mycelium grown in a lab or on grain instead. That's more sustainable, but it's a different material from the wild sclerotium, and grain-grown mycelium can be high in starch. Good labels tell you which you're getting.

What does the research say?

This is the most important section, because the gap between the marketing and the evidence is especially large for chaga.

• Almost all research is preclinical. Studies in cells and animals have looked at antioxidant activity, immune effects and blood sugar. These are early-stage findings.
• Human trials are essentially missing. There are very few published human studies of chaga, and none large or well-designed enough to support claims about immunity, energy, blood sugar or anything else.
• Antioxidant scores don't translate. You may see chaga promoted for very high "ORAC" antioxidant scores. Those are lab test-tube measurements, and they don't show any benefit in the human body.

The honest summary: chaga is a traditional drink with interesting laboratory chemistry and almost no human evidence. It is not a treatment for any condition, and claims that it fights serious disease should be ignored.

Safety: please read this before trying chaga

• Oxalates and kidneys: chaga is very high in oxalates, compounds that can form kidney stones and, in large amounts, damage the kidneys. There are published case reports of serious kidney injury in people who took large amounts of chaga powder daily for months. If you have kidney disease, a history of kidney stones, or take large amounts, avoid it.
• Blood thinners: chaga may affect blood clotting. Don't combine it with blood thinners such as warfarin, apixaban or aspirin without your doctor's advice, and stop before surgery.
• Diabetes medicines: animal research suggests chaga may lower blood sugar, so check with your pharmacist if you take diabetes medicines.
• Immune conditions: if you take immune-suppressing medicines, speak to your specialist first.
• Pregnancy and breastfeeding: avoid it, as there's not enough safety information.

Small, occasional amounts as a tea are very different from concentrated daily supplements. More is not better with chaga.

How people take it

• Tea: chunks or granules simmered gently for a long time, then strained.
• Powder or extract: in mushroom coffees, hot chocolate or smoothies.
• Drops (tinctures) and capsules: fixed amounts; follow the label.

How to choose a chaga product in Ireland

1. Source: wild sclerotium or cultivated mycelium? The label should say, and wild products should explain how they're sustainably harvested.
2. Extract type: hot-water extract, alcohol extract or whole powder.
3. Testing: heavy metals, microbes and ideally beta-glucan content.
4. Clear amounts per serving and sensible daily limits on the label.
5. No medical promises: claims about cancer, diabetes or "boosting immunity" are a red flag.
6. A real, contactable seller with an Irish or EU address.

The Irish and EU rules, briefly

Chaga is sold in food supplements and teas in the EU, but its regulatory status can depend on the form and extraction, and there are no permitted health claims for chaga. That's why responsible sellers describe it as a traditional drink rather than a remedy.

Chaga compared with other popular mushrooms

Our guides to lion's mane and reishi go into more detail.

Antioxidant claims and the ORAC problem, explained

Chaga is often marketed as one of the "highest antioxidant foods in the world", usually with a big ORAC number attached. ORAC (oxygen radical absorbance capacity) was a test-tube measure of how well a substance neutralises certain molecules in a lab. The US Department of Agriculture withdrew its ORAC database in 2012, explaining that test-tube antioxidant values don't show what happens inside the body. A high ORAC score therefore tells you very little about what a product does once you drink it. Treat any chaga marketing that leans on these numbers with caution.

Why the birch matters

Chaga takes many years to form and, once it's cut away, the tree it grew on is usually already dying from the infection. In some forests, high demand has led to over-harvesting. Responsible suppliers harvest only from mature growths, leave part of the growth in place, and can tell you the country and region the chaga came from. Some companies now grow chaga mycelium in the lab instead. That avoids pressure on wild forests, but mycelium is a different material from the wild growth, and it has been studied even less.

Making chaga tea at home

Traditionally, small chunks of dried chaga are simmered in water for an hour or more until the liquid turns dark brown, with a mild, earthy, slightly vanilla taste. The same chunks are often reused a few times. Keep the amounts modest, don't drink it in large quantities every day for long periods, and see the safety section above, especially if you have any kidney concerns or take medicines that affect blood sugar or clotting.

A note on who wrote this

cosc.ie is run by the team behind Dr. Hemp Me and the Dr. Mush Me range of mushroom drops. This guide is deliberately brand-neutral, and its safety advice applies to every product, including ours.

The bottom line

Chaga is a traditional northern tea with intriguing lab chemistry and very little human evidence. If you enjoy it, keep amounts modest, choose a tested and responsibly sourced product, and avoid it if you have kidney problems or take blood thinners or diabetes medicines without advice. And treat big health promises with the scepticism they deserve.

Related reading: Lion's mane in Ireland · Reishi in Ireland