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Limited evidenceImmunity

Horehound

White horehound is a traditional cough candy and bitter tonic whose two testable claims have both failed when checked: the FDA removed it from the approved OTC expectorant list for lack of evidence, and the one randomized diabetes trial found it lowered blood glucose by 0.64%.

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What the science says

  • Works as a cough expectorant Limited evidence

    The US FDA reviewed horehound as an OTC cough expectorant ingredient and concluded it was not generally recognized as effective, removing it from permitted OTC cough products in 1989. No placebo-controlled trial has since shown it loosens mucus or reduces cough. It remains legal as a flavoring and as a dietary supplement, which is why horehound drops still exist.

  • Lowers blood sugar in type 2 diabetes Limited evidence

    In a double-blind randomized trial of 43 poorly controlled type 2 diabetics, 21 days of Marrubium vulgare leaf infusion reduced fasting glucose by 0.64%, cholesterol by 4.16%, and triglycerides by 5.78% — all clinically meaningless. The comparator herb in the same trial (Cecropia obtusifolia) cut glucose 15.25% and triglycerides 42%. This is a rare case of an herb being directly out-performed inside its own trial.

  • Bitter digestive tonic that stimulates appetite and bile flow Limited evidence

    Horehound's marrubiin and intense bitterness plausibly trigger the standard bitter-receptor reflex increase in salivary and gastric secretion, which is the basis of its European traditional-use registration as an appetite stimulant and dyspepsia remedy. That registration is explicitly based on longstanding use, not on trial evidence; no controlled human study has measured gastric secretion or dyspepsia symptoms with horehound.

  • Anti-inflammatory and analgesic effects Limited evidence

    Aqueous horehound extract shows dose-dependent antinociceptive activity in rodent pain models and antioxidant activity in vitro, mediated largely by marrubiin and phenylpropanoids. These are animal and test-tube results with no human pain trial behind them.

Dosage & safety

Studied doseTraditional preparations: 1-2 g dried herb as an infusion up to three times daily, or 2-6 mL of 1:5 tincture daily; European traditional-use products commonly supply 4.5 g of herb per day. Horehound cough drops contain only flavoring-level amounts. The diabetes trial used a standardized leaf infusion for 21 days and did not work at that dose.
SafetyGenerally regarded as safe in food amounts; large doses cause nausea, vomiting, and diarrhoea, and the herb has documented cardiac-arrhythmia and blood-pressure-lowering effects in animals at high doses. Traditionally considered an emmenagogue and abortifacient — avoid in pregnancy. Theoretical additive effects with antihypertensives and antidiabetic drugs, though the human glucose effect proved negligible. Asteraceae/Lamiaceae contact allergy is possible. Not banned in sport. Note the name confusion: black horehound (Ballota nigra) is a different plant with a different (antiemetic) traditional use.

How to take it

TimingTiming does not matter; before meals is the traditional pattern.
With food?Either way — it is intensely bitter, so most people take it before food.
Worth knowingHorehound cough drops contain only flavouring-level amounts; they are a sweet, not a dose.

Frequently asked questions

Does horehound work for cough?

The US FDA concluded horehound was not generally recognised as effective as a cough expectorant and removed it from permitted OTC cough products in 1989 (limited evidence). No placebo-controlled trial since has shown it loosens mucus or reduces cough, and horehound drops contain only flavouring-level amounts.

Does horehound lower blood sugar?

In a randomised trial of 43 people with poorly controlled type 2 diabetes, horehound infusion for 21 days lowered fasting glucose by only 0.64%, a clinically meaningless change (limited evidence). The comparator herb in the same trial cut glucose by 15.25%.

Is horehound good for digestion?

Horehound's intense bitterness plausibly triggers the standard bitter reflex that increases digestive secretions, which is the basis of its European traditional-use registration for appetite and dyspepsia (limited evidence). No controlled human study has measured gastric secretion or dyspepsia symptoms with horehound.

Is horehound safe?

Horehound is generally regarded as safe in food amounts, but large doses cause nausea, vomiting and diarrhoea, and it is traditionally considered an abortifacient, so avoid it in pregnancy. Black horehound (Ballota nigra) is a different plant with a different traditional use.

Scientific references

Where to buy

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