Andrew Langevin
Co-Founder
Mushroom Coffee Side Effects: What to Expect and How to Avoid Problems
Mushroom coffee is generally well-tolerated, but like anything you put in your body, it can cause side effects in some people. Understanding what to expectâand who's most at riskâhelps you make informed decisions and avoid potential problems.
This guide covers the possible side effects, why they happen, and practical steps to minimize any negative reactions.
The Good News First
For most healthy adults, mushroom coffee causes fewer side effects than regular coffee:
- Lower caffeine content means fewer jitters, less anxiety, and better sleep
- Adaptogenic mushrooms may actually counteract some of coffee's negative effects
- The earthy compounds can be gentler on the stomach than acidic regular coffee
That said, side effects can and do occur. Here's what to know.
Caffeine-Related Side Effects
Even with lower caffeine (50-80mg vs 95-200mg in regular coffee), mushroom coffee still contains caffeine. Sensitive individuals may experience:
Common Caffeine Side Effects
- Jitters and restlessness (less common than with regular coffee)
- Increased heart rate
- Difficulty sleeping (if consumed too late in the day)
- Anxiety (especially in sensitive individuals)
- Headaches (from caffeine or withdrawal)
- Digestive upset
Who's Most Affected
- Slow caffeine metabolizers (genetic)
- People with anxiety disorders
- Those new to caffeine
- Pregnant women (caffeine crosses the placenta)
- People taking certain medications
How to Minimize
- Start with half a serving to assess tolerance
- Don't drink after 2 PM
- Choose brands with lower caffeine content
- Consider decaf mushroom coffee alternatives
Mushroom-Specific Side Effects
The functional mushrooms in mushroom coffee can cause their own side effects:
Digestive Issues
The most common side effect of functional mushrooms:
- Bloating or gas (from beta-glucan fiber)
- Loose stools (especially at higher doses)
- Stomach discomfort (particularly on an empty stomach)
- Nausea (rare, usually from poor quality products)
Why it happens: Beta-glucans are prebiotic fibers that feed gut bacteria. As bacteria ferment these fibers, they produce gas. This is actually a sign the mushrooms are working, but it can be uncomfortable.
How to minimize:
- Start with a lower dose and increase gradually
- Take with food rather than on an empty stomach
- Stay hydrated
- Give your gut 1-2 weeks to adjust
Allergic Reactions
While rare, some people are allergic to certain mushrooms:
- Skin rash or itching
- Hives
- Swelling (face, lips, tongue)
- Difficulty breathing (severeâseek emergency care)
Risk factors:
- Known mushroom allergies
- Mold allergies (cross-reactivity possible)
- History of food allergies
What to do: If you experience any allergic symptoms, stop use immediately. Seek emergency care for severe reactions.
Headaches
Some people report headaches when starting mushroom coffee:
- May be from caffeine adjustment
- Could be a detox reaction (controversial)
- Usually temporary (1-2 weeks)
Side Effects by Mushroom Type
Different mushrooms have different potential side effects:
Lion's Mane
Generally very well tolerated. Rare reports of:
- Skin rash (in sensitive individuals)
- Itching
- Digestive discomfort
Who should be cautious: Those with mushroom allergies, people on blood thinners (theoretical interaction)
Reishi
- Can cause dry mouth, throat, and nasal passages
- May cause dizziness in some people
- Digestive upset at high doses
- Can lower blood pressure (caution if already low)
- May affect blood clotting
Who should be cautious: People on blood thinners, those with low blood pressure, anyone scheduled for surgery
Chaga
- May lower blood sugar (caution for diabetics)
- High in oxalates (kidney stone risk with excessive use)
- May interact with blood thinners and diabetes medications
Who should be cautious: People with kidney issues, diabetics on medication, those on blood thinners
Cordyceps
- Generally well tolerated
- May cause mild digestive upset
- Could theoretically affect blood sugar
Who should be cautious: People on blood thinners, those with autoimmune conditions
Turkey Tail
- Digestive symptoms (gas, bloating) most common
- Darkened stool (harmless)
- Fingernail darkening (rare, harmless)
Who should be cautious: Generally safe for most people
Drug Interactions
Functional mushrooms can interact with certain medications:
Blood Thinners (Warfarin, Aspirin, etc.)
Several mushrooms may have mild blood-thinning effects:
- Reishi
- Chaga
- Cordyceps
Risk: Increased bleeding risk
Action: Consult your doctor before use; monitor INR if on warfarin
Diabetes Medications
Chaga and Reishi may lower blood sugar:
Risk: Hypoglycemia when combined with diabetes drugs
Action: Monitor blood sugar closely; consult your doctor
Immunosuppressants
Functional mushrooms modulate immune function:
Risk: May counteract immunosuppressive drugs
Action: Avoid or use only under medical supervision
Blood Pressure Medications
Reishi may lower blood pressure:
Risk: Excessive blood pressure drop
Action: Monitor blood pressure; consult your doctor
Who Should Avoid Mushroom Coffee
While mushroom coffee is safe for most people, certain groups should avoid it or use caution:
Avoid Entirely
- People with mushroom allergies
- Those with severe mold allergies (potential cross-reactivity)
- Anyone who experiences allergic symptoms after trying it
Use with Caution (Consult Doctor First)
- Pregnant or breastfeeding women (lack of safety data)
- People on blood thinners
- Those with autoimmune conditions
- People scheduled for surgery (stop 2 weeks before)
- Those taking immunosuppressants
- People with bleeding disorders
- Diabetics on medication
Consider Lower Doses or Alternatives
- People sensitive to caffeine
- Those with anxiety disorders
- People with digestive conditions (IBS, IBD)
- Anyone with kidney stones or kidney disease (due to Chaga's oxalates)
How to Minimize Side Effects
Start Slow
- Begin with half a serving for the first week
- Gradually increase to full serving
- This allows your body (especially your gut) to adjust
Take with Food
- Reduces digestive side effects
- Slows caffeine absorption for smoother energy
- Particularly important if you have a sensitive stomach
Stay Hydrated
- Caffeine is a mild diuretic
- Adequate water helps with any detox symptoms
- Supports overall well-being
Choose Quality Products
Poor quality mushroom coffee can cause more side effects:
- Look for fruiting body extracts (not just mycelium)
- Choose products with third-party testing
- Avoid products with unnecessary additives
Time It Right
- Don't drink too late (affects sleep)
- Avoid on completely empty stomach if sensitive
- Consistent timing helps your body adapt
Listen to Your Body
- Keep track of how you feel
- Note any symptoms and when they occur
- Adjust dosage, timing, or product as needed
When Side Effects Are Actually Good Signs
Some "side effects" indicate the mushrooms are working:
Mild Digestive Changes (First 1-2 Weeks)
Gas and bloating from beta-glucans often decrease as your gut microbiome adjusts. This temporary discomfort can mean the prebiotic fibers are feeding beneficial bacteria.
Increased Dreaming
Some people report more vivid dreams when taking Lion's Mane. This may indicate effects on neuroplasticity and sleep quality.
Temporary Energy Fluctuations
As your body adjusts to adaptogens, you may notice temporary energy changes before stabilizing at a new, improved baseline.
Frequently Asked Questions
How long do side effects last?
Most side effects (digestive issues, headaches) resolve within 1-2 weeks as your body adjusts. If symptoms persist beyond this, reduce dosage or discontinue.
Can I take mushroom coffee every day?
Yes, daily use is safe for most people and is how adaptogenic benefits build. However, some practitioners suggest periodic breaks (5 days on, 2 off, or month-long breaks occasionally).
Should I stop if I get digestive upset?
Not necessarily. Mild digestive symptoms often resolve with continued use. Try reducing the dose first. If severe or persistent, discontinue.
Is mushroom coffee safe long-term?
Research suggests functional mushrooms are safe for long-term use. Some studies have used them daily for up to a year without major issues. However, long-term human studies on mushroom coffee specifically are limited.
Can mushroom coffee cause liver problems?
Quality mushroom coffee from reputable sources should not cause liver issues. However, some cheap supplements have been contaminated with heavy metals or adulterants. Choose tested, reputable brands.
The Bottom Line
Mushroom coffee is generally safe and well-tolerated, with fewer side effects than regular coffee for most people. The most common issuesâmild digestive symptoms and caffeine sensitivityâare usually temporary and manageable.
Key takeaways:
- Start with a lower dose and increase gradually
- Take with food if you have a sensitive stomach
- Consult your doctor if you take medications or have health conditions
- Choose quality products from reputable brands
- Listen to your body and adjust as needed
If you experience severe or persistent side effects, discontinue use and consult a healthcare provider.
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