Side Effects of Mushroom Coffee: What to Consider Before You Try It

Mushroom coffee has become one of the most popular functional beverages around, but before you switch your morning cup, it's worth asking: what are the side effects of mushroom coffee? The short answer is that it's well tolerated by most people, but there are a few things to know — especially around caffeine, digestion, and how it interacts with certain conditions. Here's an honest, research-informed look.

Editorially reviewed for accuracy. Last updated: August 2026.

Key Takeaways

• Mushroom coffee is generally safe and often lower in caffeine than regular coffee, so side effects tend to be mild.
• The most common side effects are caffeine-related (jitteriness, increased heart rate) or digestive (nausea, diarrhea), especially when starting out.
• Quality matters — a well-formulated blend using fruiting-body extracts is less likely to cause issues than a cheap, filler-heavy powder.
• If you're pregnant, on medication, or have a mushroom allergy, check with your doctor first.

What Is Mushroom Coffee?

Mushroom coffee blends regular coffee (or a coffee alternative) with extracts from functional mushrooms such as Lion's Mane, Cordyceps, Reishi, and Chaga. The goal is to keep the ritual and flavor of coffee while adding the potential focus and wellness properties of mushrooms — often with less caffeine than a standard cup.

Potential Side Effects of Mushroom Coffee

Because most mushroom coffee still contains caffeine, many of its side effects are the same ones you'd get from any coffee. Others relate to the mushrooms or to individual sensitivities.

Jitteriness or Anxiety

Caffeine can cause jitters or anxious feelings in sensitive people. Mushroom coffee is often lower in caffeine, and blends that include L-theanine tend to feel smoother. If you're prone to the shakes, here's how to stop coffee jitters.

Increased Heart Rate

As a stimulant, caffeine can temporarily raise your heart rate. This is usually mild, but people with heart conditions or caffeine sensitivity should be mindful of their total daily intake.

Nausea or Upset Stomach

Some people feel mild nausea when first trying mushroom coffee, particularly on an empty stomach. Starting with a smaller serving and drinking it with food usually helps.

Diarrhea or Loose Stools

Introducing new mushroom compounds can briefly affect digestion. This typically settles as your body adjusts; easing in with a half serving can smooth the transition.

Increased Risk of Kidney Stones

Coffee (mushroom or otherwise) contains oxalates, which in excess may contribute to kidney stones in susceptible people. If you have a history of kidney stones, keep your overall intake moderate.

Allergic Reactions

Anyone with a mushroom allergy should avoid mushroom coffee. Stop use and seek medical care if you notice a rash, swelling, or difficulty breathing.

Side Effects by Mushroom Type

Most quality blends combine several mushrooms, which reduces the chance of overdoing any single one. Here's a quick look at the common ones:

• Lion's Mane — well tolerated; occasional mild digestive upset. See Cordyceps vs Lion's Mane.
• Tremella — generally gentle; prized for hydration. Learn what tremella is.
• Cordyceps — energizing; rarely may feel over-stimulating in large amounts. See cordyceps types.
• Maitake — well tolerated; may gently affect blood sugar. See maitake benefits.
• Reishi — calming; occasionally mild digestive upset or drowsiness. Learn when to take reishi.
• Shiitake / Turkey Tail — food-grade and well tolerated for most; see turkey tail benefits.

Is Mushroom Coffee Psychedelic?

No. Functional mushrooms like Lion's Mane and Cordyceps are not psychedelic and contain no psilocybin. While Lion's Mane is sometimes confused with psychedelic mushrooms, they are entirely different and mushroom coffee is non-psychoactive.

Is Mushroom Coffee Safe?

For most healthy adults, yes. It's generally considered safe and is often easier on the system than regular coffee thanks to its lower caffeine content. Choosing a quality blend and starting with a modest serving further reduces the chance of side effects. You can read more in our mushroom coffee safety overview and pros and cons.

Potential Benefits of Mushroom Coffee

People choose mushroom coffee for more than avoiding side effects. Early research suggests functional mushrooms may support:

• Steadier energy with less of a crash
• Focus and cognition (Lion's Mane is studied for nootropic support)
• A calmer, smoother caffeine experience
• Immune and antioxidant support (based on early and preclinical research)

These are areas of ongoing study rather than guaranteed outcomes, and individual results vary.

Who Shouldn't Drink Mushroom Coffee?

Check with your doctor first — or avoid it — if you are pregnant or breastfeeding, allergic to mushrooms, take blood thinners, antiplatelet, or diabetes medication, or are highly sensitive to caffeine. Children should not drink mushroom coffee without medical guidance.

How to Minimize Side Effects

Start with a smaller serving, drink it with food, stay hydrated, and choose a quality blend that uses real fruiting-body extracts rather than cheap fillers. Blending in L-theanine can also make the caffeine feel smoother.

This article is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider before adding any supplement or functional beverage to your routine, especially if you are pregnant, breastfeeding, or taking medication.

FAQ: Side Effects of Mushroom Coffee

What are the side effects of mushroom coffee?

The most common are caffeine-related (jitteriness, increased heart rate, trouble sleeping) and mild digestive effects (nausea or loose stools) when first starting. Serious reactions are rare.

Who should not drink mushroom coffee?

People who are pregnant or breastfeeding, allergic to mushrooms, highly caffeine-sensitive, or taking blood thinners or diabetes medication should check with a doctor first or avoid it.

Is mushroom coffee actually good for you?

For most people it's a well-tolerated coffee alternative that's often lower in caffeine. Early research suggests functional mushrooms may support focus, energy, and immune health, though results vary.

Does mushroom coffee contain caffeine?

Most mushroom coffees do contain caffeine, but usually less than a standard cup of coffee. Caffeine-free versions made with coffee alternatives also exist.

Can mushroom coffee help with weight loss?

Mushroom coffee is not a weight-loss product. Being lower in caffeine and sugar-free, it can fit a balanced routine, but it won't cause weight loss on its own.

Is Lion's Mane bad for the liver?

For most healthy people, Lion's Mane is well tolerated and not considered harmful to the liver. If you have a liver condition or take medication, check with your doctor first.