Herb and medicine interaction

Mulethi (licorice) and birth control pills

Yashtimadhu (mulethi, licorice) (Glycyrrhiza glabra) with birth control pills (oral contraceptives).

Evidence of interactionPending review

The short answer

Possibly, though the evidence comes from just two women. A 39-year-old woman on the pill who had used liquorice for a long time developed low potassium, swelling, weakness and a seizure, while her blood pressure stayed normal. Her doctors noted that the pill can make women more prone to liquorice side effects. Separately, a woman on the pill dropped out of a glycyrrhizin study with high blood pressure, low potassium and swelling.

Neither report shows that the pill made the reaction worse than liquorice alone would have, and neither looked at whether the pill still worked. If you take the pill, tell your doctor before you take mulethi regularly in any form, including teas, lozenges and cough products, and ask whether your blood pressure and potassium should be checked.

At a glance

What was seenHow it may workDirectionEvidence
Low potassium and fluid retention, without high blood pressure, in a woman on the pill taking liquorice[1]The pill is thought to make women more prone to glycyrrhizin's effects; not establishedLow potassium, swelling, seizureCase report
High blood pressure, low potassium and swelling in a woman on the pill during a glycyrrhizin study[2]Same; not establishedShe was withdrawn from the studyCase report

No listing is not a clearance. A missing interaction here never means a combination is safe.

The evidence, study by study

Case report, 2008 Case report

A woman taking oral contraceptives, aged 39 according to the European Medicines Agency, came to hospital with headache, weakness, swollen arms and a seizure after long-term liquorice use. Her potassium, renin, aldosterone and albumin were low, and her blood pressure was not raised. The fluid retention improved within days of stopping liquorice. The abstract does not say how much liquorice she took or which pill she was on.[1]

Glycyrrhizin dose study, 1994, as reported by the EMA Case report

The EMA's assessment report describes a woman on oral contraceptives who was withdrawn from a study of glycyrrhizin doses by Bernardi and colleagues after she developed high blood pressure, low potassium and oedema. The EMA says the clinical evidence for the pill is limited and not strong enough for specific recommendations. We have not opened the original study.[2]

What your doctor may watch for

  • Blood pressure, swelling and potassium. In the 2008 case, blood pressure was normal even though potassium was low, so a normal reading does not rule out a problem.[1]

What to tell your prescribing doctor

You can read this out, or show them this page:

“I take the pill (name) and I am taking, or planning to take, mulethi (licorice) as a tea, powder, lozenge or cough product (name and how much). There are reports of low potassium and swelling in women on the pill who took licorice. Should my blood pressure and potassium be checked?”

Withheld until review

Dose adjustments and any “no known interaction” clearance appear only after a vaidya on our medical board has reviewed this page. Why we hold these back

Questions people ask

Can mulethi stop the pill from working?

No study has measured that. Both reports describe licorice side effects in women on the pill, not pregnancies or changes in hormone levels.[1][2]

Related

Sources

  1. Francini-Pesenti F, Puato M, Piccoli A, Brocadello F. Liquorice-induced hypokalaemia and water retention in the absence of hypertension. Phytother Res. 2008;22(4):563-565. PMID 18386259.
  2. European Medicines Agency, HMPC. Assessment report on Glycyrrhiza glabra L., G. inflata Bat., G. uralensis Fisch., radix. EMA/HMPC/108395/2024, revision 1.

Updated 4 November 2026

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