Black horehound

Black horehound grows abundantly in the wild throughout the UK, mostly in England and Wales, less so in Scotland, and is easily identifiable for home remedy making (3). It is best to gather as it begins to flower in July, when the active constituents are at their highest (4,5).

Black horehound is an antiemetic, used to alleviate symptoms of nausea and vomiting, particularly when the cause is from the nervous system, such as travel sickness or an ear infection. Black horehound is also a helpful herb to use in cases of migraine, particularly if there is associated nausea. For any digestive upset such as indigestion or fullness after a meal, black horehound can be helpful as the bitter constituents stimulate the digestive processes. Due to the bitterness of the tea it can be more palatable if mixed with other herbs such as ginger, mint or fennel (Foeniculum vulgare). 

Black horehound has a calming effect on the nervous system, without being overly sedating. It can be used for mild anxiety, to relax muscle tension, or to help relaxation before bed. As a calming tea, the bitterness can be offset and complemented by herbs such as chamomile (Matricaria chamomila), passionflower (Passiflora incarnata), limeflower (Tilia spp) and lemon balm (Melissa officinalis). 

Black horehound has an expectorant action and works well for clearing congestion in the lungs or to ease a cough. It can also be supportive for menstrual issues such as an irregular cycle or menstrual cramps. It can be used externally as a wash, poultice or compress for skin infections, rashes or wounds. 

Black horehound contains diterpenes, which have a strong bitter action, increasing bile flow, stimulating digestion, and having a protective action on the liver (3).  

The relaxing and sedative action on the nervous system is due to the phenylpropanoids (arenarioside, forsythoside B, verbascoside, caffeoyl-malic acid) (6). In vitro, these phenylpropanoids have been isolated from the aerial parts of black horehound and shown to bind to benzodiazepine, dopaminergic and morphine receptors (6). This provides some pharmacological explanation for the neuro-sedative actions of black horehound. 

The antioxidant activity of the black horehound extracts has been demonstrated in vitro, with the antioxidant potential correlated to the total phenolic content and flavonoid content (5). The extracts of plants collected when flowering showed higher amounts of phenolics and flavonoids and were found to have the greatest antioxidant properties (5). The phenylpropanoids isolated from the aerial parts of black horehound have also demonstrated antioxidant activity, evidenced as an ability to scavenge reactive oxygen species in vitro (6).

Isolated constituents from black horehound (arenarioside, forsythoside B and verbascoside) have been shown to have antibacterial activity, in vitro (7). Specifically, the phenylpropanoids inhibited the growth of the gram-negative bacteria Proteus mirabilis and the gram-positive Staphylococcus aureus, including methicillin-resistant strains (MRSA) (7). This action has been replicated in more recent research with extracts of black horehound exhibiting anti-pathogenic activity to MRSA in vitro (8,9). This antibacterial activity could be due to a disruption in the way bacteria communicate (via quorum sensing), preventing virulence, biofilm formation and antibiotic resistance (10, 11). Although human clinical trials are lacking, this suggests potential for black horehound extracts to provide adjunct support alongside antibiotic treatment, particularly in resistant strains of infection.  

Emotionally, black horehound can be used to calm elevated states of hysteria, and support the low energy seen in depressive states (12). It is indicated when there is nervous debility, panic attacks, low-spirits and convulsions or fainting (12).

Since the 13th century, black horehound as been used as a herbal medicine across Europe and North Africa for the treatment of animal bites, wounds, ulcers, haemorrhoids, menstruation disorders, toothaches, sores, nervousness, stomach upset and flatulence (10). It was considered to be a sedative, diuretic, digestive, anti-inflammatory, antiseptic, antiparasitic and haemostatic herb (10).

In 1918, the British herbalist Richard Hool described the medicinal properties of black horehound as “diuretic, diaphoretic, emmenagogue, febrifuge, expectorant, pectoral, alterative, tonic, nervine, and antacid” (13). It was used for amenorrhoea, menorrhagia, dysmenorrhoea, hysteria, gravel, dropsy, stomach afflictions, coughs, hoarseness, bronchitis, consumption, loss of appetite, debility, general weakness, loss of energy, and nervous afflictions (13). 

Digestive

Black horehound was considered to be one of the most efficacious and specific remedies available for biliousness (nausea, sickness, unsettled stomach), bilious colic, and sour belching. Hool describes “the relief it affords is both prompt and certain, for if only a leaf or a piece of the stem be chewed, and the juice swallowed, it will be found to act as if a current of electricity had passed into the stomach, allaying all the symptoms momentarily” (13). The bitter constituents increase bile flow, support digestion and protect the liver, and it was traditionally used in cases of malaria to treat a swollen liver and spleen (3).

Respiratory

Black horehound was “exceedingly useful” for chronic coughs, bronchitis, tuberculosis and asthma by reducing the thickness of mucus and clearing the membranes to allow healing (13). As it not only corrects the mucus discharges, but soothes the irritation of the nerves caused by a fit of coughing. It was indicated for patients with nervous affections and was particularly useful in spasmodic tuberculosis and asthma (13). 

Reproductive

It was described as “simply wonderful” for either suppressed or excessive menstruation: “Black Horehound exerts such an influence as will restore the necessary equilibrium, it will be seen that it may be intelligently applicable to either case” (13). It was also used for labour pains and described as an excellent remedy when combined with motherwort (Leonurus cardiaca) (13).

Topical

Black horehound has a long history of topical use, with Dioscorides (40AD) suggesting the leaves be beaten with salt and applied to cure a dog bite, or mixed with honey to cleanse foul ulcers (14,15). Another use was to dry the stems to make wicks for butter lamps, and burn the leaves to repel biting insects (3).

Regarding modes of administration, it was used as an infusion, decoction, fluid extract, solid extract, powder, pills, tincture, fresh juice; or chewed in the mouth either in the fresh or dried state (13).

Digestive system

Black horehound is an excellent remedy for calming nausea and vomiting, particularly when the cause stems from the nervous system, as opposed to the stomach (4). This might include motion sickness, where the nausea is triggered by the inner ear and central nervous system (3,4). It is also valuable for nausea from emotional causes rooted in the nervous system such as anxiety, and can stimulate appetite in these cases.

Due to the bitter constituents and digestive stimulation, it is particularly helpful for nervous loss of appetite (anorexia), nervous indigestion and dyspepsia. In such cases it combines well with other gentle digestive nervines such as chamomile, lemon verbena, and lemon balm. Nausea often accompanies a migraine, and in these cases black horehound is a useful addition to a combination remedy which addresses the other individual symptoms and causes of the migraine. 

During and following a bout of gastritis, there can be considerable nausea, and gastrointestinal symptoms to which black horehound can be supportive. Black horehound has a strong antispasmodic action on the upper digestive tract, making it particularly applicable to digestive issues in the stomach, as opposed to the lower intestines (16). For nausea, a queasy stomach, biliousness, bilious colic, a sour stomach and belching it combines well with ginger (Zingiber officinale), peppermint (Mentha piperita), catnip (Nepeta cataria), and marshmallow root (Althea officinalis). 

Black horehound is indicated for nausea and vomiting during pregnancy, and recommended by many renowned herbalists and reputable resources (3,4,12,16,17,18). However, caution is warranted during pregnancy due to a possible effect on the uterus and foetal development (19,20). 

The tea is very bitter to drink and can be hard to tolerate, especially in cases of nausea, and combining with other herbs is often required. The tincture can be more palatable in cases of nausea, and can be diluted in water to be sipped, with some ginger or honey added (16).

Nervous system

Black horehound is calming for the nervous system, and clinical trials have identified that when combined with hawthorn (Crataegus monogyna), passionflower (Passiflora incarnata) and valerian (Valeriana officinalis), black horehound reduces anxiety without compromising cognitive function (21,22,23). These studies provide evidence that hawthorn, passionflower, valerian, and black horehound are a helpful combination of herbs to consider for anxiety symptoms. 

Due to the combined effect on the digestive system and the relaxant nervine action, black horehound is an effective remedy when gastrointestinal symptoms are from a nervous system origin. This can include migraines with nausea, vestibular disturbances such as middle ear infections and labyrinthitis, travel sickness and nausea due to anxiety or panic.  

Black horehound calms nervous system over-activity which can often be at the root of muscle tension, pain and spasm (3). Black horehound can be combined with herbs like cramp bark (Viburnum opulus), skullcap (Scutellaria lateriflora), valerian and Jamaican dogwood (Piscidia piscipula) to ease muscle tension and chronic pain which stems from nervous system activation. 

Black horehound can be used for mild sleep disorders (24). Insomnia can often be the result of nervous system activation, and in these cases black horehound can be added to a herbal formula to meet the patient’s individual needs. There is some evidence from animal studies that black horehound may have a mild antidepressant action (10). Therefore, the anxiolytic, antidepressant and mild sedative action suggests black horehound could be a suitable herb for certain cases of insomnia, particularly when combined with other herbs to support the root cause and other associated symptoms. 

Black horehound is also indicated when someone presents with panic attacks, fainting due to increased sympathetic nervous activation, hysteria and hypochondria (12,24).

Reproductive system

Black horehound can be used to help normalise menstrual function by suppressing a heavy or excessive menstrual bleed (menorrhagia), bringing on an absent period, and regulating oligomenorrhea or amenorrhea (3,4). The antispasmodic actions also indicate black horehound as a herb to include in a herbal mix for menstrual cramps (3).

Respiratory system

The expectorant action of black horehound will clear mucus from the lungs, making it useful for a chronic chesty cough or bronchitis (3,12). The antispasmodic action also suits black horehound to dry, tickly, spasmodic coughs and asthma (3,12). It combines well with hyssop (Hyssopus officinalis), lobelia (Lobelia inflata) (a practitioner-only herb), mullein (Verbascum thapsus) and marshmallow to support the lungs. 

Integumentary system

Black horehound has traditionally been used as a wash or poultice for wounds and infections, ulcers, skin rashes and boils (3,8,12). This use is supported by research demonstrating antibacterial activity, including against methicillin-resistant strains of Staphylococcus aureus (MRSA) (7,8,9). The antibacterial activity demonstrated by in vitro research suggests that in cases of MSRA, black horehound would be a useful herb both externally and as an internal herbal medicine (8, 9). Although there is no clinical evidence from human clinical trials, black horehound may be a herb to consider internally and externally alongside antibiotic treatment, especially against resistant strains of infection (8,9). 

Rectally, black horehound can be used as an enema or suppository for intestinal worm infestations (24,25).

There is limited clinical evidence to support the use of black horehound, and the indications for use are based on traditional use, in vitro research to determine the plant constituents, and the known actions of these constituents. Only a small number of studies have investigated pharmacological properties of isolated constituents. More detail can be found regarding isolated constituents above (Into the heart of black horehound). 

There are no clinical trials investigating black horehound as a single ingredient, although there are three clinical trials investigating it as part of a mixed ingredient herbal supplement (Euphytose®) containing Crataegus monogyna (hawthorn), Ballota nigra (black horehound), Passiflora incarnata (passionflower) and Valeriana officinalis (valerian). All three studies showed an improvement in anxiety symptoms without sedation or a reduction in cognitive function. However, it is not possible to separate the effects of the other herbs in the formula from the black horehound, limiting the evidence these studies provide for this monograph. The most recent and well controlled study is outlined below for context.

The chronic effects of a combination of herbal extracts (Euphytose®) on psychological mood state and response to a laboratory stressor: A randomised, placebo-controlled, double blind study in healthy humans

The mixed ingredient herbal supplement, Euphytose® (50 mg Valeriana officinalis, 40 mg Passiflora incarnate, 10 mg Crataegus sp., 10 mg Ballota nigra) or placebo was administered to 31 healthy participants. In this crossover study the participants took the supplement (two tablets, three times per day) for 14 days, with a 28-day washout between conditions.  Anxiety (State-Trait Anxiety Inventory), mood and physiological measures of stress (heart rate, galvanic skin response, salivary α-amylase and cortisol levels) and cognitive performance were measured before and after a multitasking stressor.

After the herbal supplementation period there was a significant reduction in subjective anxiety, and stress (lower salivary α-amylase and galvanic skin response) in response to the multitasking stressor, compared to the placebo. There was no difference in cognitive performance across each treatment or between the two conditions. This suggests that despite the reported sedating effects of some of the extracts contained within the treatment, the herbal supplement decreased stress and anxiety without any changes to negative effects on cognitive performance (23).

Neuro-sedative and antioxidant activities of phenylpropanoids from ballota nigra

In this in vitro study, five phenylpropanoids (arenarioside, forsythoside B, verbascoside, caffeoyl-malic acid) were isolated from an alcohol extract of the aerial parts of black horehound (6). The isolated compounds are able to bind to the benzodiazepine, dopaminergic, and morphine receptors in rodent muscle and brain tissues. This data provides some pharmacological explanation for the neuro-sedative actions of black horehound (6).

The study also demonstrated antioxidant activities of these phenylpropanoids, against reactive oxygen species liberated from inflammatory white blood cells. The antioxidant activity, evidenced by an ability to scavenge reactive oxygen species, was comparable to the antioxidant supplement N-acetyl cysteine (NAC) (6). 

Antibiotic treatment  

Two studies are presented here to outline the potential for black horehound to be used as an adjunct therapy alongside antibiotic treatment. It should be noted that these are in vitro studies, using cell cultures, and are not clinical trials, but they do outline a potential indication for use from the research.

Effects of extracts from Italian medicinal plants on planktonic growth, biofilm formation and adherence of methicillin-resistant Staphylococcus aureus 

Using cultured methicillin-resistant Staphylococcus aureus, the study reported the water extract (but not alcohol extract) of black horehound inhibited biofilm formation. The water extract was a crude extract of the whole herb, using 1 g herb per 50 ml water, which has practical significance for the replication of this extract at safe dosages.

The black horehound water extract was one of only five of the 168 plant extracts which inhibited the biofilm formation. The authors concluded that the results validate the efficacy if black horehound as a topical application for skin and soft tissue infections (8).  

Quorum sensing inhibitors of Staphylococcus aureus from Italian medicinal plants

The study measured the production of δ-hemolysin (a toxin produced by Staphylococcus aureus which plays a role in bacterial virulence) in cultured Staphylococcus aureus.

Black horehound was one of only three of the 104 plants tested which lowered the production of δ-hemolysin. This demonstrated the alcohol extract to have anti-quorum sensing activity (ability to disrupt bacterial communication systems known as quorum sensing), suggesting a mechanism for preventing biofilm formation, reducing virulence factor production, and inhibiting antibiotic resistance (9).  

The Latin name Ballota comes from the Greek ballo which means ‘to reject’, as the strong offensive odour means cattle and other farm animals reject it, leaving it remaining in the fields they are grazing (2,14). The smell of the fresh plant also accounts for several of the common names including stinking horehound (2).

Black horehound is native to Europe and North Africa (Algeria, Morocco, Tunisia), and has been introduced and naturalised across the UK and North America (Alabama, Maryland, New York, Wisconsin); South America (Argentina) Kazakhstan, Kirgizstan, West Siberia, and New Zealand (27,30). It can be found in forests, woodlands, shrublands, hedgerows, road verges and waste ground, grasslands, shady meadows, along water courses on disturbed nutrient rich soils near habitations and urban areas (27).

There is no CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) Legislation on trade of this species (32). 

Black horehound does not have a status ranking and there is no information on the distribution although it appears in several states  across North America (33). It does not appear on the U.S. Endangered Species act or the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (33).  

The International Union for Conservation of Nature (IUCN) most recently conducted a European assessment of Ballota nigra in 2012 and listed it as “Least Concern (LC) (27). They state that the species is widely distributed across Europe, with a large overall population (27). Despite local declines it is considered unlikely to be declining fast enough to qualify for listing in a more threatened category (27). The Vascular Plant, Red Data List, For Great Britain also listed black horehound horehound as least Concern (LC) as it is widespread and abundant (31). A plant is considered LC when it has been evaluated against the criteria and does not qualify for critically endangered, endangered, vulnerable or near threatened (31).

Habitat loss and over-harvesting from the wild are two of the biggest threats faced by medicinal plant species. There are an increasing number of well-known herbal medicines at risk of extinction. We must, therefore, ensure that we source our medicines with sustainability in mind.

The herb supplement industry is growing at a rapid rate and until recent years a vast majority of medicinal plant produce in global trade was of unknown origin. There are some very real and urgent issues surrounding sustainability in the herb industry. These include environmental factors that affect the medicinal viability of herbs, the safety of the habitats that they are taken from, as well as the welfare of workers in the trade.

The botanical supply chain efforts for improved visibility (transparency and traceability) into verifiably sustainable production sites around the world is now certificated through the emergence of credible international voluntary sustainability standards (VSS). 

Read our article on Herbal quality & safety: What to know before you buy and Sustainable sourcing of herbs to learn more about what to look for and questions to ask suppliers about sustainability.

Herbal medicines are often very safe to take; however, their safety and efficacy can be jeopardised by quality issues. So, it is important to buy herbal medicines from a reputable supplier, from sources known to test their herbs to ensure there is no contamination, adulteration or substitution with incorrect plant matter, as well as ensuring that recognised marker compounds are at appropriate levels in the herbs.

Some important quality assurances to look for are certified organic labelling, the correct scientific/botanical name, and the availability of information from the supplier about ingredient origins. A supplier should be able to tell you where the herbs have come from, what contaminants are not in the herb, and what the primary compounds are.

Propagation is by root division in spring, growing well in well drained, nitrogen rich soil in full sun (3,29). Also grows from seed directly into the garden, and will continue to self-seed (14). It is both frost and drought resistant (18).

Upset tummy tea

This tea blend is for sipping if you feel nauseous due to travel sickness, a tummy bug, or an emotional cause such as anxiety. It will ease the nausea, settle the tummy, stimulate the digestion and ease acidic sensation in the stomach that can accompany nausea. It can also help if you feel a little nauseous after a meal or have overeaten. 

Ingredients 

• Black horehound 15g
• Peppermint 10 g
• Lemon verbena 10 g
• Marshmallow root 10 g
• Dried ginger root 5 g

Method

Mix together the dried herbs to store in an airtight container. Using 5 g (~1 teaspoon) per  cup, add the herbs to a teapot, cover in boiling water and leave to steep for 10–15 minutes. Sip slowly, drinking between one and three cups per day.

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