Awaiting clinical review. This entry is sourced but has not yet been signed off by a pharmacist or clinician.

Althaea officinalis (root)

Marshmallow root

Marshmallow root is a soothing, mucilage-rich herb that regulators accept for irritation of the mouth and throat with dry cough, but only on the basis of long-standing use; the human research is thin and mostly uncontrolled. The EU regulator lists no known side effects. The main practical caution is that it may delay the absorption of other medicines, so the EU regulator advises taking it half an hour to an hour apart from them.

Written by

Healthy and Herbal editorial team

Updated

29 September 2026

Pale pink marshmallow flowers on the plant

At a glance

Last reviewed 29 September 2026

Evidence

Limited

Best for

Dry cough, throat irritation

Typical form & use

Root macerate, 0.5–3 g in 150 ml water

Onset

Same night

Safety

Take 30–60 min apart from other medicines. No interactions in our data.

Check with your medications →

What it's used for

Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.

Use	Evidence	What the research shows
Mouth and throat irritation with dry cough	Limited	The EU regulator recognises marshmallow root as a demulcent for this, on long-standing use alone. In two uncontrolled pharmacy surveys of 822 people using a lozenge or syrup made from one aqueous root extract (STW42), most reported a good effect, often within 10 minutes, with only 3 minor adverse events. There was no placebo group, so these results cannot separate the extract from natural recovery or the soothing effect of any lozenge or syrup. A 2020 narrative review (not a systematic review) concluded the extract works for dry cough, but it mixes animal and clinical studies.^1,2,4
Dry mouth (reduced saliva)	Limited	In a small Croatian trial, 60 people with low saliva flow were randomised to one of three products used four times a day for 2 weeks; only 15 used marshmallow root. Dry-mouth intensity fell whichever product was used, but a thermal-spring-water spray improved quality of life more than the root did. There was no placebo arm, and the abstract does not say how the root was prepared.³
Mild stomach discomfort	Traditional	The EU regulator lists relief of mild gastrointestinal discomfort as a traditional use, based on long-standing use only. We found no human trial we could open that tests it, so we rate it on the traditional record alone. The regulator advises seeing a doctor if symptoms last longer than 2 weeks.¹

How much

Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.

Cough and throat (adults)

0.5–3 g root in 150 ml water¹

As a macerate (soaked, not boiled), several times a day. The EU monograph's maximum is 15 g of herbal substance a day.

Stomach discomfort (adults)

2–5 g root in 150 ml water, 3 times a day¹

Herbal tea macerate, taken by mouth only. Use it immediately after preparing it. Maximum 15 g a day.

How long

1 week (cough), 2 weeks (stomach)¹

If symptoms last longer than that during use, the EU regulator advises consulting a doctor or qualified health care practitioner.

Timing · The EU monograph advises taking it at least half an hour to an hour before or after other medicines, because it may delay their absorption. For throat irritation it can be used orally or as an oromucosal (held-in-the-mouth) preparation.With food? · No source we read gave guidance on taking it with food.How long to trial · The EU monograph says to see a doctor if cough or throat irritation lasts longer than 1 week, or stomach discomfort longer than 2 weeks, and sooner if breathlessness, fever or purulent (pus-like) sputum appears.

How people take it

Cold macerate (tea)0.5–3 g root in 150 ml waterThe traditional preparation in the EU monograph: the comminuted root is soaked in water, not boiled.

Syrup or lozengeFollow the product labelThe EU monograph gives syrup doses by the amount of root in the macerate (for adults 10–15 ml, 3–5 times a day). The surveys we read used an aqueous extract in a lozenge or syrup.

Dry or liquid extractFollow the product labelThe EU monograph covers water extracts and a 1:1 25% ethanol liquid extract; strengths differ, so labels are not interchangeable.

Safety

Who should avoid

Pregnancy and breastfeeding — safety not established, EU regulator advises against
Children under 3 — not recommended for cough and throat use
Children under 12 — not established for the stomach-discomfort use
Known allergy to marshmallow root — the monograph lists it as a contraindication
Breathlessness, fever or pus-like sputum — see a doctor rather than self-treat

Known interactions

No interactions in our data. Absence of a flag is not clearance.

Questions people ask

Does marshmallow root work for a dry cough?

It is a recognised traditional remedy, and users of one extract lozenge and syrup mostly reported a good effect in two surveys. Those surveys had no placebo group, so we cannot say how much was the extract itself and how much was ordinary soothing and recovery.

Should I take marshmallow root at the same time as my medicines?

The EU regulator says it may delay the absorption of other medicines taken at the same time. As a precaution it advises leaving half an hour to an hour before or after them. It lists no specific drug interactions.

Is marshmallow root safe?

The EU regulator lists no known side effects and no reported overdose, and the two surveys recorded 3 minor adverse events in 822 people. Its safety in pregnancy and breastfeeding has not been established, and no fertility data exist.

Sources

Last reviewed 29 September 2026 · Next review March 2027 · How we rate evidence