According to Drugs.com, more than 192 (682 brand and generic names) medications are known to interact with licorice.
Even though it is a dietary supplement, licorice can potentially interact with several medicines. Real licorice products (including some candies, beverages, supplements and extracts) can cause significant side effects. However, many licorice products contain little or no real licorice. For instance, red licorice does not contain any real licorice and some black licorice products contain anise flavoring instead of licorice.
Even though it seems like a harmless substance, licorice can cause some dangerous side effects. You should immediately report any of these side effects to your doctor. These licorice side effects include but are not limited to:
• High blood pressure (hypertension)
• Signs of congestive heart failure (CHF), such as: water retention, rapid weight gain, swelling of the feet or hands, difficulty breathing
• Low blood potassium (hypokalemia)
• An irregular heart rhythm (arrhythmia)
• Severe muscle pain
• Signs of hormonal changes, such as: missed periods (in women), a low sex drive, impotence (in men)
• Muscle weakness
• Signs of an allergic reaction, such as: rash, itching, hives, swelling of the mouth or throat, wheezing, difficulty breathing
Many of the serious licorice side effects are thought to be caused by one specific component of licorice, known as glycyrrhizin. Deglycyrrhizinated licorice (DGL) products, which have had the glycyrrhizin component removed, may be less likely to cause these serious side effects.
If you think you are experiencing a licorice side effect, please let your healthcare provider know immediately. Also, let your healthcare provider know if you develop something that "just does not seem right." While it may not be a side effect of licorice, your healthcare provider will be able to diagnose and treat the problem.
Several medications may cause potentially negative drug interactions with licorice.