What is licorice?
What we commonly call licorice is a plant drug consisting of the rhizomes and roots of the homonymous plant (Glycyrrhiza glabra, Fabaceae family).
Excessive consumption of this sort of delicacy, with its typical aromas and flavors, can cause some problems, especially for those suffering from high blood pressure.
Because the pressure increases
In fact, licorice roots contain from 6 to 12% of glycyrizin (glycoside of glycyrrhizic acid), in which the sugar component is made up of two glucuronic acid molecules.
The sweetening power of this glycoside is estimated to be 50-100 times higher than that of sugar; in addition to this and numerous other interesting phytotherapeutic properties (antiviral, anti-ulcer, hepatoprotective, laxative, anti-inflammatory, expectorant and gastroprotective), licorice and the glycerizin contained in it also boast a hypertensive action. 
This effect is expressed in the liver and kidneys, where a metabolite of glycyrrhizic acid reduces the metabolism of corticosteroids through the inhibition of the enzyme 11-B-hydroxysteroid-dehydrogenase. This effect increases the activity of cortisol in the kidney, comparable to that exerted by aldosterone, inducing a state of hyper-pseudo-aldosteronism in the body.
In addition to an increase in blood pressure, therefore, excess liquorice can cause alterations in the water and electrolyte balance, with a decrease in blood potassium (hypokalemia), salt and water retention (edema), decrease in diuresis and - in the most severe cases - alteration of muscle contractility and heart rhythm.
Contraindications and Precautions
As explained above, licorice should be consumed with particular moderation - if not avoided - by patients suffering from arterial hypertension, hypokalaemia and chronic renal failure.
Particular caution should be paid to the joint use of licorice and:
- ACE inhibitors, diuretics or other medicines for high blood pressure (which can reduce their therapeutic activity);
- laxatives (increased risk of hypokalaemia);
- antiarrhythmic drugs;
- birth control pills (which in itself can slightly increase blood pressure);
- corticosteroids (licorice may potentiate their effect).
It should be noted the presence on the market of deglycirized preparations, which however - in addition to the hypertensive effect and other possible side effects - lose most of the therapeutic virtues of licorice.
