Here are the ones people most often experience:
💊 Metformin – Common Side Effects
1️⃣ Digestive Upset (Most Common)
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Nausea
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Diarrhea
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Stomach cramps
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Gas or bloating
👉 Often improves after a few weeks. Taking it with food helps.
2️⃣ Metallic Taste
Some people notice a strange or metallic taste in their mouth.
3️⃣ Loss of Appetite
Mild appetite suppression is common (sometimes helpful for weight loss).
4️⃣ Vitamin B12 Deficiency (Long-Term Use)
Metformin can reduce B12 absorption over time, possibly leading to:
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Fatigue
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Numbness/tingling in hands or feet
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Memory issues
👉 Periodic B12 testing is recommended for long-term users.
5️⃣ Weight Changes
Many people experience mild weight loss, though not everyone does.
6️⃣ Low Blood Sugar (Rare Alone)
Metformin rarely causes hypoglycemia by itself, but risk increases if combined with insulin or other diabetes medications.
7️⃣ Lactic Acidosis (Very Rare but Serious)
A rare complication, more likely in people with:
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Severe kidney disease
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Advanced liver disease
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Heavy alcohol use
Symptoms include:
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Severe weakness
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Rapid breathing
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Muscle pain
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Extreme fatigue
This is uncommon but requires emergency care.
8️⃣ Headache
Occasional mild headaches.
9️⃣ Dizziness
Especially when first starting.
🔟 Gastrointestinal Sensitivity to Dose Increases
Side effects often flare when dosage is raised too quickly.
🩺 Important: When to Talk to Your Doctor
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Persistent diarrhea lasting more than a few weeks
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Signs of B12 deficiency
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Severe fatigue or muscle pain
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Kidney problems
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Any sudden worsening symptoms
💡 Ways to Reduce Side Effects
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Take with meals
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Start at a low dose and increase gradually
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Ask about extended-release (ER) metformin, which is gentler on the stomach
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Monitor B12 levels annually if on long-term therapy
Bottom Line
Metformin is generally safe, effective, and well-studied, but side effects should absolutely be discussed — not ignored.
If you’d like, tell me:
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Are you taking regular or extended-release?
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How long have you been on it?
I can give more tailored guidance.