Cardiovascular and circulatory disorders are one of the leading causes of illness and death worldwide. When managing these conditions affecting the heart and blood vessels, caution is advised. However, the use of medicinal plants can carry an invisible but very real risk. Certain natural remedies interact directly with blood pressure, blood flow or essential medication.
How can you combine the use of medicinal plants with heart health without taking risks? This comprehensive guide examines the dangerous links between plant-based active ingredients and your circulatory system.
Why do liquorice and medicinal plants that raise blood pressure cause blood pressure to rise?
High blood pressure (HBP) is an acute or chronic increase in blood pressure in the arteries. It is one of the major risk factors leading to the development of atherosclerosis. It also leads to serious complications affecting the brain, heart, eyes or kidneys.
What is hypertension?
Medically speaking,high blood pressure is defined as systolic readings (when the heart contracts) regularly exceeding 140 mm Hg (or 14 cm) at rest. Furthermore, a diagnosis is made when the pressure reaches 85 mm Hg (or 8.5 cm) during diastole (the phase when the heart relaxes and fills).
These values must, of course, be adjusted physiologically for children (values are normally lower). Similarly, in older people, the values are naturally higher.
In addition to genetic factors, high blood pressure requires strict lifestyle and dietary changes: stopping alcohol and smoking, reducing obesity through a low-fat diet, managing stress, engaging in appropriate physical activity, and reducing salt intake. A mild form of hypertension may also occur in pregnant women and resolve spontaneously after childbirth.
Herbal remedies to avoid in cases of high blood pressure (liquorice, mint, coffee, maté)
In cases of high blood pressure, the use of liquorice is strictly contraindicated. It contains glycyrrhizin, a compound that retains salt and water in the body. This causes blood pressure to rise dangerously. To keep your blood pressure under control, you should also limit or avoid other medicinal plants with stimulating or vasoconstrictive effects, such as mint, tea, coffee and maté. These plants excessively stimulate the heart rate.
What are the risks of interaction between anticoagulant treatments and medicinal plants?
Blood clotting disorders manifest either as insufficient clotting causing haemorrhages (such as genetic haemophilia), or as excessive clotting leading to thrombosis. To treat or prevent myocardial infarction and venous thrombosis, doctors prescribe anticoagulants and antiplatelet agents. These treatments target coagulation factors, proteins produced by the liver that require vitamin K.
How do medicinal plants affect platelet aggregation?
Combining certain medicinal plants with anticoagulant treatments poses a major risk of adverse events. Very common medicinal plants such as ginger, ginseng and white willow possess natural antiplatelet properties. When consumed alongside medical treatment, they excessively thin the blood. Furthermore, they dangerously increase the risk of internal bleeding. When it comes to diet, caution is also advised regarding the excessive consumption of foods with strong antiplatelet effects (garlic, onions, tomatoes, omega-3 and omega-6 fatty acids).
The critical case of St John’s wort and natural remedies that induce drug interactions
St. John’s wort is the king of drug interactions. As a powerful enzyme inducer, it accelerates the breakdown of substances by the liver. This drastically reduces the effectiveness of crucial molecules such as clopidogrel or vitamin K antagonists. Conversely, excessive consumption of foods rich in vitamin K (cabbage, spinach) blocks the action of anticoagulants. This therefore exposes the patient to a risk of blood clots. The diagnosis and monitoring of these conditions rely on strict tests (platelet count, prothrombin time – PT, activated partial thromboplastin time – aPTT). Furthermore, the uncontrolled use of herbal remedies can completely skew these tests.
Why do venous insufficiency and varicose veins find a false friend in certain laxative herbal remedies?
Venous return disorders affect a large number of adults and significantly impair quality of life.
Whilst herbal medicine offers solutions for leg comfort, certain categories of plants turn out to be false friends.
Haemorrhoidal flare-ups: why do senna and buckthorn make the situation worse?
Haemorrhoids are varicose veins, i.e. dilations and inflammations of the veins in the anal and rectal mucosa. Benign but very uncomfortable, they affect one in three adults, particularly those aged between 40 and 65. They manifest as pain during bowel movements, itching and rectal bleeding (bleeding). In the event of an acute haemorrhoidal flare-up, a haemorrhoidal thrombosis may form. This extremely painful clot can make sitting impossible. Causes include bowel dysfunction, obesity, a sedentary lifestyle, pregnancy, or a diet low in fibre and high in spices, alcohol and coffee.
The main pitfall with haemorrhoids is attempting to treat constipation with chemical laxatives or medicinal plants containing anthraquinones (such as senna or buckthorn). These plants cause a massive rush of blood to the pelvic region. This congests the anal veins and dramatically worsens the flare-up. To relieve internal haemorrhoids (visible via anoscopy) or external haemorrhoids (protruding), treatment relies on a high-fibre diet. If necessary, medical procedures (photocoagulation, liquid nitrogen) may be recommended.
Venous return disorders and post-phlebitic syndrome
Chronic venous insufficiency is characterised by impaired blood return to the heart, often linked to venous hypertension caused by damaged valves. It causes a sensation of heaviness in the legs, cramps, paraesthesia (tingling), oedema, varicose veins, and even stasis ulcers. This condition affects up to 5% of the population in the United States.
One form of this condition, post-phlebitic (or post-thrombotic) syndrome, develops in 20 to 50% of patients following deep vein thrombosis (phlebitis). The risk is increased in cases of recurrence, proximal thrombosis or a high body mass index. Diagnosis is based on medical history, clinical examination and venous ultrasound. Furthermore, the management of this venous insufficiency focuses on compression (wearing compression stockings), rest with the legs elevated and wound care.
Did you know? The immune system is also particularly sensitive to natural active ingredients. The wrong choice can reactivate an autoimmune disease or trigger hypersensitivity reactions. Read our comprehensive guide to immunity and medicinal plants.
Sources:
- Izzo & Ernst (2009). Interactions between herbal medicine and prescribed drugs. Br J Clin Pharmacol.
- Penninkilampi et al. (2017). Liquorice-induced hypertension: a systematic review. J Hum Hypertens.
- Institutional reports from the European Medicines Agency (EMA) on the safety of anthraquinone-containing plants.
FAQ: How can you use medicinal plants without compromising your heart and circulation?
Why is liquorice strongly discouraged in cases of high blood pressure?
Liquorice contains glycyrrhizin, an active compound that disrupts sodium excretion and causes water retention. This mechanism increases blood volume and causes a critical rise in blood pressure, which exacerbates high blood pressure (HBP).
What are the risks of taking herbal remedies alongside anticoagulant treatment?
Herbal remedies such as ginger, ginseng or white willow possess natural anti-platelet properties. If taken alongside anticoagulant medication, they can make the blood too thin, which dangerously increases the risk of severe internal bleeding.
How does St John’s wort interact with cardiovascular medicines?
St. John’s wort is a powerful enzyme inducer. It strongly stimulates the liver enzymes responsible for breaking down medicines, thereby accelerating their elimination. Consuming this herb therefore drastically reduces the effectiveness of vital treatments such as anticoagulants or antiplatelet agents.
Why should senna and buckthorn be avoided during a haemorrhoid flare-up?
Senna and buckthorn are stimulant laxatives rich in anthraquinones. As well as irritating the colon, they cause a massive rush of blood to the pelvic region, which immediately congests the anal veins and painfully exacerbates haemorrhoid flare-ups.
