
Herbal Actions
S - Z
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Saponins are naturally occurring compounds found in a wide range of plants. They are named for their soap-like quality, they foam when agitated in water, and have an amphipathic nature, meaning they interact with both water and fat. This allows them to influence cell membranes and aid the absorption of other herbal constituents.
In herbal medicine, saponins are valued for their expectorant, anti-inflammatory, immune-modulating, and antifungal properties. They stimulate mucous membranes, promoting the clearance of mucus from the lungs and respiratory tract, making them useful in managing coughs and bronchial congestion.
Saponin-containing herbs include:
Horse Chestnut (Aesculus hippocastanum) – improves venous tone and reduces capillary fragility.
Nettle (Urtica dioic) – highly nutritive with mild expectorant and anti-inflammatory activity.
Mullein (Verbascum thapsus) – supports respiratory health through its soothing and expectorant effects.
Calendula (Calendula officinalis) – a wound-healing vulnerary and gentle lymphatic stimulant.
Yarrow (Achillea millefolium) – astringent, antimicrobial, and mildly expectorant.
Saponins can also enhance nutrient absorption and improve the bioavailability of other herbal compounds by increasing cellular permeability. Some, like those found in yarrow and nettle, may exertgentle hormonal or adaptogenic activity over time.
While beneficial, saponins can be irritating in high concentrations, particularly to the gastrointestinal tract or red blood cells. Used with care, they offer valuable support across respiratory, circulatory, immune, and integumentary systems.
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Sedatives are herbs that calm the nervous system, reduce overactivity, and promote rest, both mental and physical. Unlike synthetic sedatives, herbal sedatives tend to be gentle and supportive, working with the body to ease tension, anxiety, irritability, or insomnia without suppressing natural rhythms.
They often act by enhancing the effect of inhibitory neurotransmitters like GABA (gamma-aminobutyric acid), helping to slow nervous system activity and reduce the body's stress response. Many sedatives also have antispasmodic effects, relieving muscular tension and restlessness that can accompany nervous exhaustion.
Notable sedative herbs include:
Valerian (Valeriana officinalis) – a strong sedative with muscle-relaxant properties, commonly used for insomnia and nervous agitation
Passionflower (Passiflora incarnata) – especially helpful where anxiety, circular thoughts, or overthinking prevent restful sleep
Lemon Balm (Melissa officinalis) – calming, uplifting, and useful for nervous indigestion or mild anxiety
Chamomile (Matricaria chamomilla) – gentle enough for children, supports sleep and digestion while easing emotional tension
Tilia spp. (Tilia spp.) – relaxing to both the nerves and the cardiovascular system, helpful in stress-related headaches or palpitations
Skullcap (Scutellaria lateriflora) – a reliable herb for nervous exhaustion, twitching, and tension, especially after long-term stress
Sedatives may be used on their own or in synergy with nervines and adaptogens, particularly in formulas aimed at sleep support, recovery from burnout, or emotional resilience. They are often taken as teas, tinctures, or infused oils, depending on the desired effect and intensity.
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Stimulants are herbs that increase physiological activity in the body, often by enhancing circulation, raising metabolic rate, or activating the nervous system. In contrast to sedatives, stimulants promote energy, alertness, and responsiveness, though herbal stimulants tend to act more gently and sustainably than synthetic ones like caffeine or amphetamines.
Herbal stimulants may work by increasing blood flow, warming the periphery, or mildly stimulating the adrenal system. Many have a warming nature, making them useful in cases of coldness, sluggish digestion, fatigue, or depression.
Commonly used stimulants include:
Ginger (Zingiber officinale) – a circulatory stimulant that warms the body, supports digestion, and enhances absorption of other herbs.
Cayenne (Capsicum annuum) – a potent stimulant that increases peripheral blood flow, supports the heart, and relieves stagnation.
Rosemary (Salvia rosmarinus) – a cerebral stimulant that improves focus and memory while supporting poor circulation
Peppermint (Mentha × piperita) – mildly stimulating to the digestive and nervous systems, refreshing and uplifting.
Thyme (Thymus vulgaris) – stimulating to both the respiratory and digestive systems, with antimicrobial properties.
Stimulant herbs are often used short-term to revive energy, dispel cold, or lift low mood. In formulation, they may be paired with adaptogens or warming carminatives to support vitality, mental clarity, and circulation.
Caution is advised with strong stimulants in individuals with high blood pressure, nervous sensitivity, or heat signs.
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Styptics are herbs that help stop bleeding by contracting tissue and promoting clot formation. They are a type of astringent, with a more specific action on broken capillaries or superficial wounds, making them valuable in both internal and external applications.
Styptic herbs work by vasoconstriction (narrowing blood vessels), encouraging platelet aggregation, or physically sealing minor wounds. Externally, they are commonly used as powders, compresses, or washes for cuts, grazes, or nosebleeds. Internally, they may be used cautiously for conditions like heavy menstrual bleeding or haemorrhoids, always under guidance.
Useful styptic herbs include:
Yarrow (Achillea millefolium) – a classic styptic that helps slow bleeding and also has anti-inflammatory and antimicrobial properties.
Shepherd’s Purse (Capsella bursa-pastoris) – traditionally used for heavy menstrual or uterine bleeding.
Plantain (Plantago spp.) – helps tighten tissue, stop bleeding, and soothe damaged skin.
Calendula (Calendula officinalis) – mildly styptic with added vulnerary and antimicrobial benefits for wound care.
Oak bark (Quercus robur) – another traditional styptic, high in tannins and commonly used in compresses and sitz baths.
Styptics are typically high in tannins, which help contract and tone tissue. These herbs are especially helpful in first aid kits, post-partum care, or for minor bleeds and abrasions.
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Tonics are herbs that strengthen, nourish, or restore function to specific body systems when taken consistently over time. They are typically gentle and non-stimulating, working by supporting the natural tone and vitality of tissues, organs, or physiological processes. Unlike fast-acting remedies, tonics are often used long-term, especially during convalescence, depletion, or chronic imbalance.
Tonic herbs may be nutritive, organ-specific, or adaptogenic, depending on their primary actions. They often support resilience, improve energy, and help restore balance after illness, stress, or fatigue.
Notable tonic herbs include:
Nettle (Urtica dioica) – a rich nutritive tonic high in vitamins and minerals, supportive of the blood, kidneys, and skin
Oats (Avena sativa) – a nervous system tonic that gently rebuilds strength during burnout or exhaustion
Hawthorn (Crataegus spp.) – a cardiovascular tonic that supports heart function and strengthens circulation
Dandelion root (Taraxacum officinale) – a liver tonic that aids detoxification and digestion
Milk Thistle (Silybum marianum) – a hepatoprotective liver tonic known for its regenerative properties
Ashwagandha (Withania somnifera) – a key adaptogenic tonic supporting endocrine and immune balance
Tonics are usually taken as teas, decoctions, tinctures, or powders and are best suited to chronic or constitutional support. They can form the foundation of long-term herbal care and are often paired with nervines, adaptogens, or bitters for broader support.
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Topical application refers to the use of herbs directly on the skin or external tissues. This includes preparations such as creams, salves, oils, poultices, compresses, washes, and baths. Topical remedies allow herbs to work locally on a specific area, offering relief from inflammation, infection, irritation, pain, or injury.
Many herbs applied topically have vulnerary, antimicrobial, anti-inflammatory, analgesic, or astringent actions. The skin absorbs certain constituents, allowing some herbs to exert effects just beneath the surface or even enter systemic circulation.
Commonly used herbs in topical preparations include:
Calendula (Calendula officinalis) – a classic vulnerary, antimicrobial, and anti-inflammatory herb ideal for healing wounds and soothing inflamed skin
Plantain (Plantago spp.) – draws out toxins, soothes bites and stings, and promotes tissue repair
Yarrow (Achillea millefolium) – antimicrobial, styptic, and healing, used in washes and compresses for cuts and grazes
Mullein (Verbascum thapsus) – often infused into oil for earaches or chest rubs, with demulcent and anti-inflammatory properties
Comfrey (Symphytum officinale) – promotes rapid tissue regeneration; often used for bruises, sprains, and bone injuries (use topically only with care due to pyrrolizidine alkaloids)
Topical application is especially useful when internal use is inappropriate or when targeting a localised condition. These preparations are often well-tolerated and form a key part of traditional herbal first aid and skin care.
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Transdermal refers to the absorption of herbal constituents through the skin and into the bloodstream, allowing herbs to exert systemic effects without passing through the digestive tract. While all transdermal applications are technically topical, not all topical preparations are designed or able to be absorbed transdermally.
For a substance to pass through the skin’s protective barrier, it usually requires certain molecular properties or a delivery medium (such as oil, alcohol, or DMSO) that enhances penetration. Transdermal application can be especially helpful for those with digestive sensitivities or when a slow, sustained effect is desired.
Examples used in transdermal or semi-transdermal ways include:
Comfrey(Symphytum officinale) – applied as a compress or infused oil to support healing of sprains, bruises, and fractures (used with caution due to pyrrolizidine alkaloids)
Mullein (Verbascum thapsus) – infused into oil for use around the ear or chest, where some active compounds may absorb through local tissues
Chilli (Capsicum annuum) – used in creams or plasters to relieve pain through counter-irritant and circulatory-stimulating effects
Rosemary (Salvia rosmarinus) – used in infused oils or liniments for muscular aches, promoting circulation and warmth
Arnica (Arnica montana) – widely known for its transdermal action in trauma and bruising (external use only)
While transdermal delivery is gentler than injections or oral medications, it still allows herbs to act systemically. However, skin absorption varies by herb, individual, and preparation, so effects may be milder or slower than internal use.
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Terpenes are aromatic compounds found in many plants, particularly in essential oils. They are responsible for the distinct scents and flavours of herbs like lavender, peppermint, and thyme, but beyond their fragrance, terpenes have potent therapeutic actions. They play a key role in a plant's defence system and often possess antimicrobial, anti-inflammatory, antioxidant, and relaxant properties.
There are hundreds of types of terpenes, including monoterpenes, sesquiterpenes, and diterpenes, each with specific physiological effects. Some interact with the nervous system, others influence the respiratory or immune systems, and many enhance circulation or reduce inflammation.
Terpene-rich plants include:
Thyme (Thymus vulgaris) – high in thymol, a monoterpene with strong antimicrobial and respiratory-stimulating effects.
Peppermint(Mentha × piperita) – contains menthol, a terpene with cooling, analgesic, and digestive-supportive properties.
Rosemary (Salvia rosmarinus) – rich in cineole and camphor, which promote circulation, memory, and respiratory health.
Valerian (Valeriana officinalis) – contains sesquiterpenes thought to contribute to its sedative and antispasmodic actions.
Chamomile (Matricaria chamomilla) – includes bisabolol and chamazulene, which are soothing and anti-inflammatory.
Terpenes are highly volatile, meaning they evaporate easily, this is why they’re prominent in aromatherapy and steam inhalation. They’re often extracted via distillation to produce essential oils but are also present in teas, tinctures, and infused oils when prepared carefully.
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Vulnerary herbs support the healing of wounds, cuts, abrasions, and damaged tissues, both externally and internally. Their actions may include promoting cell regeneration, reducing inflammation, preventing infection, and tightening tissues to aid closure and repair.
Vulneraries are typically used in topical applications such as salves, washes, poultices, and creams, but some also work systemically when taken internally, for example, in supporting mucosal healing in the digestive tract.
These herbs often overlap with antimicrobial, anti-inflammatory, and astringent categories and are foundational in traditional first-aid herbal care.
Excellent vulnerary herbs include:
Calendula (Calendula officinalis) – a key vulnerary used to promote clean healing and reduce inflammation in cuts, wounds, and minor burns
Plantain (Plantago spp.) – draws out impurities, soothes irritation, and promotes tissue regeneration
Yarrow (Achillea millefolium) – antimicrobial, styptic, and wound-healing, often used in fresh or dried form for cuts and grazes
Comfrey (Symphytum officinale) – supports rapid tissue repair and bone healing (external use only; internal use discouraged due to pyrrolizidine alkaloids)
Mullein (Verbascum thapsus) – soothing and demulcent, often used for skin and respiratory tract irritation
Althaea (Althaea officinalis) – internally used vulnerary for mucosal tissues (mouth, throat, gut, urinary tract)
Vulnerary herbs are essential in herbal first-aid kits and skin care routines. When used thoughtfully, they help the body heal efficiently while reducing the risk of infection or scarring.
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Volatile oils are the aromatic, highly evaporative compounds found in many herbs, especially those used in aromatherapy and traditional medicine for their scent and therapeutic properties. Also known as essential oils, they are made up of complex molecules including terpenes, phenols, and ketones, which are responsible for a herb’s distinctive fragrance and many of its medicinal actions.
Volatile oils are extracted primarily by steam distillation, though they are also present in teas, tinctures, and infused oils when fresh or dried aromatic herbs are used.
These oils often exhibit antimicrobial, antispasmodic, carminative, circulatory stimulant, and nervine properties. Because they are quickly absorbed and fast-acting, they are especially useful for acute conditions, such as respiratory congestion, digestive upset, or mental fatigue.
Volatile oil–rich plants include:
Peppermint (Mentha × piperita) – cooling, antispasmodic, and digestive; rich in menthol
Thyme (Thymus vulgaris) – antimicrobial and warming; contains thymol and carvacrol
Rosemary (Salvia rosmarinus) – stimulating to circulation and cognition; rich in cineole and camphor
Chamomile (Matricaria chamomilla) – calming and anti-inflammatory; contains bisabolol and chamazulene
Sage (Salvia officinalis) – antiseptic, astringent, and hormone-modulating
Valerian (Valeriana officinalis) – contains volatile constituents thought to contribute to its sedative effect
Volatile oils are powerful and should be used with care, especially in concentrated forms like essential oils. In whole-plant preparations, they are often gentler and still highly effective.
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Warming herbs increase circulation, stimulate digestion, and bring heat and movement to the body. These herbs are often pungent or spicy in taste and are commonly used to dispel cold, dampness, and stagnation, both in physical and energetic terms. They are especially helpful in individuals who feel cold, fatigued, sluggish, or depleted.
Warming herbs act on various systems including the digestive, circulatory, and respiratory systems. Many have stimulant, diaphoretic, or carminative properties, and they are frequently used to enhance the actions of other herbs in a formula.
Classic warming herbs include:
Ginger (Zingiber officinale) – circulatory stimulant, digestive aid, and immune supporter; useful for cold hands and feet, nausea, and sluggish digestion
Chilli (Capsicum annuum) – intensely warming; increases blood flow, relieves cold-related pain, and supports cardiovascular health
Thyme (Thymus vulgaris) – warming and antimicrobial; used for respiratory infections and sluggish digestion
Rosemary (Salvia rosmarinus) – promotes circulation, uplifts the mind, and improves peripheral warmth
Sage (Salvia officinalis) – gently warming and drying; supports digestion, cognition, and hormonal balance
Garlic (Allium sativum) – stimulates circulation, supports immunity, and clears cold/damp stagnation
Warming herbs are often used in colder months, for cold-natured conditions, or constitutionally cold individuals. Care should be taken in those with signs of excess heat, irritation, or inflammation.
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Wildcrafting is the traditional practice of harvesting plants from their natural, uncultivated environments for food, medicine, or craft. Rooted in ancestral knowledge, wildcrafting emphasises working in harmony with nature, and when done responsibly, it encourages deep observation, connection, and respect for the land.
Ethical wildcrafting considers plant population, habitat, timing, and sustainability. Only abundant plants should be harvested, and always in a way that allows regrowth, often guided by the “1-in-20” rule (take no more than 5% of a population). Plants that are rare, threatened, or slow to regenerate should not be wildcrafted at all.
Wildcrafting requires plant identification skills, knowledge of local ecology, and an understanding of the medicinal part of each plant (root, leaf, flower, seed, etc.). It also honours reciprocity, giving thanks, giving back, and taking only what is needed.
Many herbs are commonly wildcrafted, including:
Cleavers (Galium aparine) – best gathered fresh in spring for lymphatic support
Plantain (Plantago spp.) – grows abundantly in disturbed areas; used fresh for stings, bites, and wound care
Yarrow (Achillea millefolium) – a classic wild herb with many first-aid uses
Stellaria (Stellaria media) – or chickweed; soft, soothing, and nutritious when gathered carefully
Nettle (Urtica dioica) – rich in minerals; best harvested young with gloves!
Responsible wildcrafting fosters a deep relationship with place, reminding herbalists to be stewards as well as students of the land.
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Xerostomia refers to the condition of dry mouth, often caused by reduced or absent saliva production. It can result from medication use, dehydration, nerve damage, radiation therapy, or systemic conditions such as diabetes or autoimmune disorders. Left unaddressed, it may contribute to difficulties with swallowing, speaking, oral infections, or dental decay.
In herbal medicine, xerostomia is often addressed with demulcent and moistening herbs that soothe and hydrate mucous membranes, stimulate gentle salivation, and reduce inflammation.
Helpful herbs for xerostomia include:
Marshmallow (Althaea officinalis) – rich in mucilage; coats and soothes irritated oral and digestive tissues
Plantain (Plantago spp.) – demulcent and mildly astringent; supports mucosal healing
Licorice (Glycyrrhiza glabra) – a classic moistening demulcent with mild anti-inflammatory effects
Marshmallow (Althaea officinalis) – a common herb for mucosal dryness and lining airway and digestive tracts.
Slippery Elm (Ulmus rubra) – another classic demulcent, though increasingly difficult to source sustainably
Hydrating teas, cold infusions, and lozenges made from these herbs can provide symptomatic relief and promote tissue resilience. Encouraging hydration, reducing caffeine and alcohol intake, and addressing underlying causes are also important in managing xerostomia holistically.
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Yin and Yang are foundational concepts in Traditional Chinese Medicine (TCM) used to describe the dynamic balance of opposing yet complementary forces in the body, nature, and life. Though not part of Western herbal tradition, many modern herbalists draw on these principles to better understand constitution, energetics, and systemic balance.
Yin represents the cooling, moistening, inward, and restorative aspects of the body. Yin is linked with fluids, rest, nourishment, and substance.
Yang represents warming, drying, outward, and activating functions, such as metabolism, movement, and heat.
When Yin and Yang are out of balance, symptoms may arise, for example:
Yin deficiency may manifest as dryness, heat, restlessness, or burnout
Yang deficiency may present as coldness, fatigue, low mood, or poor circulation
Though not traditionally described this way, some Western herbs may be energetically categorised:
Cooling/Yin-supportive herbs:
Lemon Balm (Melissa officinalis) – calming, moistening
Chamomile(Matricaria chamomilla) – anti-inflammatory and soothing
Marshmallow(Althaea officinalis) – demulcent and hydrating
Warming/Yang-tonifying herbs:
Yin/Yang theory can be a useful lens for thinking about herbal energetics, tailoring remedies to individual constitutions, and supporting deeper systemic harmony.