Licorice Root

Licorice root (Glycyrrhiza spp.) can help relieve cough symptoms because it contains demulcent/expectoral and anti-inflammatory compounds (notably glycyrrhizin and related flavonoids). However there are no high-quality clinical trials showing licorice cures or reliably treats pertussis (whooping cough); pertussis is a bacterial infection that requires prompt medical care and usually antibiotics (macrolides) and public-health measures.

• Demulcent / soothing action. Licorice root is rich in mucilage and other compounds that coat and soothe irritated throat and bronchial mucosa (this helps reduce cough reflex sensitivity and relieves throat soreness). This kind of symptomatic relief is why it’s been used traditionally for “coughs and bronchial catarrh.” MDPI+1
• Anti-inflammatory and expectorant effects. Compounds in licorice (glycyrrhizin and flavonoids) show anti-inflammatory effects in lab studies and may help reduce airway inflammation and help mobilize mucus. That can make coughing less painful and help clear secretions. MDPI+1
• Antimicrobial / immunomodulatory activity in vitro and animal models. Glycyrrhizin and derivatives have reported antiviral and antibacterial actions in laboratory studies and can modulate immune responses; animal studies and in-vitro work show support for antitussive and antimicrobial properties, but these are preclinical or small trials, not proof of clinical effectiveness against Bordetella pertussis. MDPI

Summary: licorice can provide symptomatic relief (soothing, expectorant, antitussive effects) and has molecules that show antimicrobial/anti-inflammatory activity in labs — but that does not equal proven clinical cure of pertussis. For treatment of pertussis itself follow standard medical guidance (antibiotics and supportive care). CDC

Common traditional / modern ways people use licorice for coughs:

• Licorice tea (decoction): simmer 1–2 g of dried licorice root (or 1 tsp cut root) in ~250–300 mL water for 5–10 minutes, strain and sip warm up to 2–3 times/day. (Many herbal guides give similar home-brew recipes — exact amounts vary between sources because there is no single standardized dose.) The Nest - The Nest
• Herbal cough syrups / lozenges / tinctures: commercial cough formulas often contain standardized licorice extract as part of a multi-herb syrup (to act as demulcent and expectorant). Follow the product label. Homemade syrups combining licorice decoction with honey are common home remedies (honey for >1 year old only). PlantHealth+1
• Deglycyrrhizinated licorice (DGL): DGL removes most glycyrrhizin (the compound mainly responsible for side effects such as hypertension). DGL is often used for digestive uses (ulcer support) and is sometimes suggested where long-term glycyrrhizin exposure is a concern. If choosing licorice primarily for throat smoothing, DGL may reduce safety risks—but it may also remove some of the glycyrrhizin-linked pharmacology. Darwin Nutrition
• Standardized extracts: some supplements list glycyrrhizin content (e.g., “Glycyrrhizin 20–25%”). Because glycyrrhizin drives most warnings, many practitioners prefer either short-term use or using DGL preparations. Staqc

How to use in practice (practical recommendations):

• Use licorice preparations only as symptomatic supportive care (to soothe throat and ease cough discomfort). Do not delay seeking medical care or antibiotics for suspected or confirmed pertussis. CDC
• Prefer short courses (days–low weeks) rather than continuous long-term use to reduce risk of glycyrrhizin accumulation. Medsafe
• If you want lower risk, consider DGL products (follow label dosing) or limit glycyrrhizin to established safe limits (see warnings below). Alzheimer's Drug Discovery Foundation

• There are preclinical studies and small animal experiments showing antitussive and anti-inflammatory activity (e.g., murine cough models). ResearchGate
• There are laboratory (in vitro) and review articles showing glycyrrhizin and derivatives have broad antiviral and some antibacterial activity, and they discuss mechanisms (membrane effects, enzyme inhibition, immune modulation). These are promising mechanistic studies but do not prove clinical efficacy against pertussis. MDPI
• A few clinical trials test licorice (or DGL) for other indications (peptic ulcer disease, chronic cough of mixed causes)—for example DGL in ulcer trials—but I could not find robust randomized controlled trials showing licorice root cures or shortens clinical pertussis. Trials for “chronic cough” are heterogeneous and do not specifically address Bordetella pertussis infection. MDPI

Summary: the best quality evidence for licorice is mechanistic, animal, or trials for other respiratory conditions — no reliable RCT evidence supports licorice as an effective antimicrobial therapy for pertussis. For pertussis, authoritative public-health guidance recommends antibiotics (macrolides) because pertussis is a bacterial infection and antibiotics reduce infectivity and complications. MDPI