Based on NIH | Can metformin cause anxiety or worsen existing anxiety, and how common is this side effect?

Metformin and anxiety: what we know

• Metformin is not commonly linked to causing anxiety on its own, and most people taking metformin do not report anxiety as a direct side effect. ^[1] However, anxiety-like symptoms can occur indirectly in a few situations: during episodes of low blood sugar (hypoglycemia) when metformin is combined with other glucose‑lowering drugs, during significant gastrointestinal (GI) upset that affects well‑being, or in rare metabolic complications such as lactic acidosis. ^{[2] [3]}

How metformin could relate to anxiety

• Hypoglycemia overlap: Metformin by itself rarely causes hypoglycemia, but when used with insulin or insulin‑releasing medicines (e.g., sulfonylureas), low blood sugar can occur and may feel like anxiety fast heartbeat, sweating, shaking, jitteriness, irritability, confusion. ^{[1] [2]} These “adrenergic” symptoms can be misread as anxiety or panic. ^[3]
• GI discomfort and quality of life: Metformin’s most common side effects are GI diarrhea, nausea, abdominal discomfort, bloating and these can lower physical and mental quality of life, which in turn may worsen perceived anxiety in some people. ^{[4] [5]}
• Very rare metabolic issues: Severe, persistent lactic acidosis with metformin is rare, typically linked to kidney, liver, or hypoxic conditions; panic‑like episodes were described in an old case report with elevated lactate that resolved after stopping the drug. ^[1] Routine use within prescribing precautions keeps this risk very low. ^{[1] [1]}

How common is anxiety with metformin?

• Product labeling for metformin emphasizes GI side effects as common; anxiety is not listed as a common direct adverse reaction for metformin alone, and rates are not provided as a metformin‑specific, dose‑related event the way GI reactions are. ^[4] In contrast, labeling for metformin products highlights the symptoms of hypoglycemia (e.g., fast heartbeat, sweating, shaking/jittery, irritability, confusion) to help users recognize low blood sugar these can feel like anxiety but are signs of hypoglycemia risk when combined with other agents. ^{[2] [3]}
• Diabetes itself is associated with a higher likelihood of anxiety disorders or elevated anxiety symptoms compared with people without diabetes, so new or worsening anxiety in someone with diabetes is not necessarily caused by metformin. ^[6]

Practical signs to watch for

• Possible hypoglycemia symptoms: fast heartbeat, sweating, trembling/jitteriness, irritability, confusion, headache, dizziness, hunger, drowsiness. These may overlap with anxiety and warrant checking glucose, especially if taking metformin with insulin or a sulfonylurea. ^{[2] [3]}
• GI side effects that may affect well‑being: diarrhea, nausea/vomiting, abdominal discomfort, flatulence most common early in therapy or after dose increases. ^[4] Persistent GI upset can reduce mental quality of life and contribute to anxious feelings. ^[5]

What to do if anxiety appears after starting metformin

• Check blood sugar during symptoms: If readings are low, treat hypoglycemia promptly and discuss your regimen with your clinician, particularly if you also take insulin or a sulfonylurea. ^{[2] [3]}
• Tackle GI side effects: Taking metformin with meals, slow dose titration, or using extended‑release formulations may reduce GI symptoms and indirectly improve mood and anxiety levels. ^[1] If GI symptoms remain significant, discuss alternatives. ^[5]
• Review medical factors: Kidney function, alcohol use, or conditions causing poor oxygenation should be reviewed to keep lactic acidosis risk low (again, rare with proper prescribing). ^[1]
• Consider other causes: Anxiety is more common in diabetes overall and may reflect life stressors, glucose variability, sleep issues, thyroid problems, or other medications; a comprehensive review can help tailor care. ^[6]

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Quick reference table

Topic	Key points	How common?
Direct anxiety from metformin	Not recognized as a common, dose‑related adverse effect in metformin labeling; evidence is limited to rare/indirect reports. [4]	Uncommon/undetermined
Hypoglycemia‑like symptoms (can feel like anxiety)	Fast heartbeat, sweating, shaking/jittery, irritability, confusion most relevant when metformin is combined with insulin or secretagogues. [2] [3]	Possible depending on combination therapy
GI side effects and mood impact	Diarrhea, nausea, bloating, abdominal pain are common early and can lower mental quality of life. [4] [5]	Common for GI symptoms; mood impact varies
Rare metabolic complication	Lactic acidosis is rare with appropriate use; an old case report linked panic‑like episodes with elevated lactate that resolved after stopping therapy. [1]	Very rare

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Bottom line

• Anxiety is not a well‑established, common side effect of metformin itself, but symptoms that mimic anxiety are well described in the context of hypoglycemia when metformin is used with other glucose‑lowering drugs. ^{[2] [3]} GI side effects can also indirectly worsen perceived anxiety by lowering quality of life. ^{[4] [5]} Overall, the likelihood that metformin alone directly causes anxiety appears low, while diabetes as a condition is associated with higher rates of anxiety regardless of metformin use. ^[6]