Licorice
Glycyrrhiza glabra, Glycyrrhizin, and Documented Testosterone Suppression
Evidence grade 3 of 5, Mixed. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Not FDA evaluated (food flavoring and herbal supplement)
Reference only. Not medical advice.
What can go wrong
The dominant clinical danger of licorice is not its testosterone effect but glycyrrhizin-induced pseudohyperaldosteronism: hypertension, low potassium, fluid retention, and in severe cases arrhythmia. The FDA has warned that eating large amounts of black licorice can cause dangerous potassium drops, especially in adults over 40. Men taking blood-pressure or potassium-affecting medications should be cautious. Deglycyrrhizinated licorice (DGL) lacks glycyrrhizin and should not carry these effects.
This is something to take to a clinician. The Atlas can tell you what is known about licorice in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Licorice root, the source of natural licorice flavoring, contains glycyrrhizin (glycyrrhizic acid), which has documented effects on adrenal and gonadal steroids. A widely cited letter in the New England Journal of Medicine (Armanini et al., 1999) reported that 7 healthy men consuming licorice supplying about 0.5 g of glycyrrhizin per day for a week had roughly a 35% fall in serum testosterone, recovering after stopping. Replication has been mixed: a repeat in 17 men found a significant ~25% decrease, while another study in 31 men found only a non-significant ~9.5% salivary decrease. This is one of the few natural agents with real human evidence of lowering testosterone.
A flavoring agent with a published, replicated signal for LOWERING testosterone.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
How it is supposed to work
Glycyrrhizin and its metabolite inhibit enzymes in steroid synthesis, including 17,20-lyase and 17-beta-hydroxysteroid dehydrogenase steps, reducing testosterone production. Glycyrrhizin also inhibits 11-beta-hydroxysteroid dehydrogenase type 2, allowing cortisol to act on mineralocorticoid receptors, which causes the well-known pseudohyperaldosteronism (hypertension, hypokalemia) of licorice excess.
Small studies, but a real and biologically plausible effect
The original report was tiny (7 men) and replication was inconsistent in magnitude, so the precise effect size is uncertain. But the direction is consistent with a known enzymatic mechanism, making licorice a credible testosterone-lowering agent at meaningful glycyrrhizin doses, unlike most herbs claimed to raise testosterone. The more reliable and dangerous effect of licorice excess is on blood pressure and potassium, not on testosterone.
What people get wrong
Often saidLicorice is just candy and harmless
ActuallyReal licorice contains glycyrrhizin, which can lower testosterone and, more dangerously, raise blood pressure and drop potassium. The FDA has warned about black licorice and dangerous potassium loss.
Often saidLicorice boosts testosterone or vitality
ActuallyThe human evidence points the opposite way: glycyrrhizin tends to lower testosterone. Any 'adrenal support' framing does not change that direction.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
What we do not know
- What is the true dose-response and effect size, given inconsistent replication?
- Is the testosterone effect clinically meaningful at culinary licorice intakes, or only at supplement-level glycyrrhizin?
At a glance
- Active compound
- Glycyrrhizin (glycyrrhizic acid)
- Landmark report
- NEJM 1999 (7 men, ~35% T drop)
- Replication
- ~25% in 17 men; ~9.5% (NS) in 31 men
- Direction
- LOWERS testosterone
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Licorice. A short entry is not a safe entry.
- Timeline. We have not built the dated record of research and regulatory events.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- Where we land. We have not taken a position on this yet.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Armanini et al. (reduction of serum testosterone in men by licorice, NEJM letter)1999
7 healthy men taking licorice (~0.5 g glycyrrhizin/day) for a week had roughly a 35% drop in serum testosterone, recovering after stopping
Armanini et al. (follow-up in 17 men)2003
Reported a significant ~25% decrease in serum testosterone with licorice consumption
Sigurjonsdottir et al. / Josephs et al. (salivary testosterone with licorice)2000s
A study in 31 men found only a non-significant ~9.5% decrease in salivary testosterone, highlighting inconsistent replication