Bittersweet

Other Names

Amara DulcisBitter nightshadeBittersweet nightshadeBlue bindweedBlue nightshadeClimbing nightshadeDulcamaraDulcamarae stipitesDwaleEuropean bittersweetFellenFellenwortFelon bloomFelonwoodFelonwortFever twigFevertwigMorelMortalPheasant berryPoison bittersweetPoisonberryPoisonflowerPoisonous nightshadeScarlet berrySkawcooSnake berrySnakeberrySolani dulcamarae stipitesSolanum dulcamaraSolanum dulcamara var. dulcamaraSolanum dulcamara var. villosissimumStaff vineStipites dulcamaraeTether-devilTrailing bittersweetTrailing nightshadeViolet bloomWolf grapeWolfgrapeWoody nightshade

Synopsis

Bittersweet (Solanum dulcamara L.): A Comprehensive Reference

1. Identity and Nomenclature

1.1 Botanical and Chemical Names

The plant most commonly designated "bittersweet" in the herbal and dietary-supplement literature is Solanum dulcamara L., a species of vine in the genus Solanum — which also includes the potato and the tomato — of the family Solanaceae. Its common names include bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis, climbing nightshade, felonwort, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry, trailing bittersweet, trailing nightshade, violet bloom, and woody nightshade. Its principal botanical synonym is Dulcamara, and it is also known as woody nightshade.

The name "bittersweet" has a specific etymological origin. It was coined by the 16th-century English herbalist William Turner, who translated the medieval Latin names for the plant — dulcamarum, dulcis amara, or amara dulcis — referring to the woody stem bark, which if tasted is at first sweet and then turns very bitter in the mouth. The genus name Solanum derives from the Latin word solamen, meaning "comforting or soothing," while the species name dulcamara is derived from a word meaning "bittersweet."

The common name "bittersweet" is also applied to a second, botanically unrelated plant: Celastrus scandens L. (American bittersweet, climbing bittersweet; family Celastraceae). This North American vine was given the name "bittersweet" by colonists in the 18th century because its fruits resembled those of common nightshade (Solanum dulcamara), which was also called bittersweet. Today, "American bittersweet" is the accepted common name of C. scandens in large part to distinguish it from an invasive relative, C. orbiculatus (Oriental bittersweet), from Asia. The present article is organized to cover both species, beginning with the more extensively documented S. dulcamara, with a dedicated section on C. scandens.

1.2 Natural Sources and Distribution

Solanum dulcamara is native to Europe and Asia. It was introduced to North America for ornamental and medicinal purposes and became widespread by the late 1800s, and is now considered an invasive weed in most American states and Canadian provinces. This perennial vine climbs via slender, often reddish stems up to 3 m long, bearing pointed, ovate leaves and clusters of 1–2 cm purple-blue flowers. Flowers are blue-violet, star-shaped, with protruding yellow anthers, and bloom from May to September. The plant forms clusters of green, ovoid berries that turn red when ripe.

1.3 Medicinal Plant Part and Common Preparations

Dulcamara, as the drug is known, consists of the stems and branches of Solanum dulcamara. The stems are gathered when the plants are about two or three years old, cut into short pieces, and dried. The drug occurs in commerce in short cylindrical pieces about 6 mm in diameter.

The EU herbal monograph on woody nightshade stem (Solani Dulcamarae Stipites) recognizes the traditional use of the comminuted herbal substance in the form of an infusion or decoction applied cutaneously only for the symptomatic relief of mild recurrent eczema. The infusion or decoction (at room temperature) is applied to the affected area on a clean dressing. Oral use is not recognized, because of concerns about its toxicity. Woody nightshade stems are also used to prepare the cosmetics ingredient Solanum Dulcamara Stem Extract (CAS no. 84696-50-4), regarded as having "skin conditioning" properties.

Historically, a wider variety of preparations were employed. These included Extractum Dulcamarae Fluidum (Fluid Extract of Dulcamara), dosed from half to one dram. Modern formulations noted in European regulatory dossiers include herbal teas and capsules, including combination products with 6.25% S. dulcamara extract, as well as an ethanol 30% extract (1:5) at 10 g per 100 g of final product.

2. Traditional and Historical Use

2.1 European Herbal Traditions

S. dulcamara has a history of use in herbal medicine dating back to classical times, and there are few ailments and complaints for which it has not at some time been recommended. The main uses were in treating rheumatism, skin diseases, and as a purgative. The herbalists Gerard (English), Boerhaave (Dutch), and Linnaeus (Swedish) all spoke highly of its medicinal virtue, and S. dulcamara continued to feature in the British Pharmacopoeia until 1907 for skin complaints, after which it was dropped from modern pharmacy.

In medieval Europe, Solanum dulcamara appeared in Herbarius texts of the 1400s, praised by herbalists like John Gerard as a remedy for skin ulcerations and glandular swellings. Numerous historical names refer to supposed magical properties that garlands of the plant — on account of its red berries — were thought to offer against witches and sudden illness.

In the 19th-century Eclectic medical tradition of North America, dulcamara was prescribed for conditions linked to exposure to cold and damp. It was recommended as a remedy in chronic skin diseases of a pustular, vesicular, or scaly type, and was also tried in cases of pudendal itching. In traditional European medicine, S. dulcamara was used to treat feverish conditions and reduce inflammation; preparations such as teas or tinctures were administered in controlled doses owing to the plant's toxic nature.

A traditional use in chronic itching eczema, chronic bronchitis, asthma, rheumatism, gout, and obstinate skin eruptions has been described for Solanum dulcamara stipites. Most references emphasize the treatment of eczema.

2.2 Spread to South Asia

S. dulcamara is non-native to South Asia. It first arrived in India with Jesuit missionaries in the 17th century, then gradually featured in vernacular health manuals by the 19th century under vernacular names like "mithi kateli." During the British colonial period, Anglo-Indian practitioners experimented with bittersweet nightshade, comparing it to Rasna (Pluchea lanceolata) for rheumatic pains.

2.3 American Bittersweet (Celastrus scandens): Traditional Use

Celastrus scandens (climbing bittersweet) was employed medicinally by a number of native North American Indian tribes, though it is scarcely used in modern herbalism. C. scandens roots were used by Native Americans and pioneers to induce vomiting, to treat venereal disease, and to treat symptoms of tuberculosis.

The root was used as a diaphoretic, diuretic, and emetic; it was a folk remedy for chronic liver and skin ailments (including skin cancer), rheumatism, leucorrhoea, dysentery, and suppressed menses. A strong compound infusion, usually combined with raspberry leaf tea, was used to reduce the pain of childbirth. A poultice of the boiled root was applied to obstinate sores and skin eruptions. Externally, the bark was used as an ointment on burns, scrapes, and skin eruptions.

Historically, American bittersweet was used by Native Americans for food and medicinal purposes; they also used it in decorations, and it is still commonly used in dry flower arrangements and for winter decor.

3. Key Constituents and Active Compounds

3.1 Steroidal Glycoalkaloids

S. dulcamara contains steroidal alkaloid glycosides — including α-solamarine, β-solamarine, solasonine, and solamargine — steroidal saponins (based on the aglycones yamogenin, tigogenin, and diosgenin), and polyhydroxynortropane alkaloids, including a family of calystegines.

Within S. dulcamara, different plant parts produce differing alkaloid profiles: solanine accumulates predominantly in unripe fruits, solasodine in flowers, and beta-solamarine in roots. The stems of bittersweet contain glycoalkaloids of solasodine, soladulcidine, and 5,6-dehydrotomatidine, but also spirostanol glycosides and furostanol glycosides of proto-yamogenin. The latter are responsible for the bitter taste of the drug.

The content of solanine in the flowers and green fruit of potato is about 1%, but compared to Solanum tuberosum, the content of steroid alkaloid glycosides in S. dulcamara stipites is low (0.07–0.4%).

Bittersweet also contains the alkaloid solanine and the amorphous glucoside dulcamarin, to which the characteristic bittersweet taste is due. Sugar, gum, starch, and resin are also present. Additional identified compounds include solaceine, soladulcamarine, solamargenine (throughout the plant), solasodine (root), solanidine, soladulcidine and tomatidine (fruits), atropine (seeds), and the saponins diosgenin, tigogenin, and yamogenin.

Tissue-culture studies of the soladulcidine variety of S. dulcamara have confirmed the isolation of soladulcidine, solasodine, and the corresponding neutral spirostanes tigogenin and diosgenin.

3.2 Structural Classification

Solanum species are a unique source of several pharmacologically important lead molecules, especially steroidal alkaloids such as solasodine, solasonine, solamargine, and various other medicinally useful alkaloids. The spirosolan category is composed of a tetrahydrofuran and piperidine spiro-linked bicyclic system with an oxa-azaspirodecane structure (as in solasodine), and the solanidane type is derived by an indolizidine ring where a tertiary nitrogen connects the two rings (as in solanidine).

3.3 Established and Proposed Mechanisms of Action

S. dulcamara is used traditionally as an anti-inflammatory agent against rheumatic diseases and chronic diseases of the skin; the furostanol and spirosolanol glycosides are discussed as the active constituents for these effects.

Neurological signs observed in solanine toxicity result from direct neurotoxic effects of solanidine in addition to acetylcholinesterase inhibition. Due to its structural similarities to cardiac glycosides, solanine and solanidine also have positive inotropic effects.

Following ingestion, solanine is poorly absorbed from the gastrointestinal tract, causing local irritation. In the GI tract, solanine is also hydrolyzed to solanidine, which is absorbed and can produce neurologic, cardiovascular, and respiratory systemic effects.

Regarding saponin-class mechanisms, research on closely related Solanum species has shown that steroidal saponins inhibit inflammatory mediators in vitro. Studies on steroidal saponins from S. nigrum berries evaluated their inhibitory effects on nitric oxide and IL-6 and IL-1β production induced by lipopolysaccharide in macrophage cell lines; compound 1 exhibited significant inhibition of NO production with an IC50 of 9.7 μM, and other compounds significantly inhibited LPS-induced IL-6 and IL-1β production.

After oral administration of solasodine citrate (the salt of the aglycone solasodine), cardiotonic effects and a desensitizing effect were observed in patients with rheumatic arthritis and ankylosing spondylitis (data cited from Hänsel et al., 1994 in the EMA assessment report).

4. Scientific Evidence by Area of Use

4.1 Dermatology: Eczema and Skin Conditions

This is the best-documented therapeutic application, supported by regulatory recognition. Solanum dulcamara stems are approved by the German Commission E for external use as supportive therapy in chronic eczema. The EU herbal monograph on woody nightshade stem similarly recognizes the traditional use of the comminuted herbal substance in the form of an infusion or decoction applied cutaneously for the symptomatic relief of mild recurrent eczema, with oral use not recognized because of concerns about toxicity.

The EMA's assessment report describes an open observational study. The study diagnoses were atopic eczema (380 patients), contact dermatitis (106 patients), and other diagnoses with eczema. Symptoms including itching, formation of wheals, erythema, weeping, and scalification were generally recorded to improve during the trial, and 526 patients completed the four-week study. The EMA assessment report concludes, however, that no data from clinical trials of adequate quality are available, and only safety information from some open clinical studies has been reviewed. The overall evidentiary basis is therefore classified as traditional use — not as established efficacy.

At the laboratory level, the alkaloids solanine (from unripe fruits), solasodine (from flowers), and beta-solamarine (from roots) have been found to inhibit the growth of E. coli and S. aureus. Solanine and solasodine extracted from S. dulcamara also showed antidermatophytic activity against Chrysosporium indicum, Trichophyton mentagrophytes, and T. simil, suggesting potential activity against ringworm.

4.2 Anti-Inflammatory and Antirheumatic Activity

S. dulcamara L. (Solanaceae) is used traditionally as an anti-inflammatory agent against rheumatic diseases and chronic diseases of the skin. The EMA assessment notes that no information on the clinical pharmacology of the herbal substance or herbal preparation is available from well-designed clinical trials.

Preclinical in vitro evidence is consistent with anti-inflammatory activity. In a published study, plant parts of S. dulcamara with a high content of specific alkaloids (solanine from unripe fruits, solasodine from flowers, beta-solamarine from roots) were extracted and screened for antibacterial activity against human-pathogenic bacteria including Enterobacter aerogenes, Escherichia coli, and Staphylococcus aureus. Solasodine from flowers of S. dulcamara inhibited the growth of Escherichia coli and Staphylococcus aureus; however, no significant activity was observed against Enterobacter aerogenes.

No robust randomized controlled trials of S. dulcamara preparations for rheumatic conditions in humans have been identified in the peer-reviewed literature. The traditional use for rheumatism is well-documented historically but the current scientific evidence is limited to preclinical and observational data.

4.3 Anticancer Research (Preclinical Only)

One study assessed solanine's toxicity using a standard animal model for breast cancer. Solanine notably inhibited 4T1 cancer cell proliferation in a dose-dependent and time-dependent manner, with an IC50 value for the 4T1 cancer cell line of 34 µM within 24 hours, decreasing to 17 µM after 48 hours. A minimal effect of solanine was observed on human fibroblast normal cell lines. Significant chemotherapeutic and chemoprotective effects of solanine were observed against breast cancer cells via apoptosis induction, cell proliferation inhibition, and angiogenesis suppression.

Solasodine and solamargine demonstrated strong cytotoxicity against human hepatoma Hep3B cells. Derivatives of solamargine, ursolic acid, and solasodine also demonstrated noteworthy cytotoxicity against in vitro human liver cancer cell lines (PLC/PRF/5).

The anti-nutrient properties and human toxicity of Solanum steroidal glycoalkaloids are well-documented, while they have more recently attracted researchers' attention for pharmacological properties including anticancer, antibiotic, and anti-inflammatory effects. For instance, Coramsine (SBP002) was an experimental chemotherapeutic drug composed of two steroidal glycoalkaloids (solamargine and solasonine) isolated from Solanum linneanum.

All anticancer evidence relating directly to S. dulcamara constituents is currently preclinical (cell lines and animal models). No clinical trials in humans have been completed for anticancer use of preparations derived specifically from this plant.

4.4 Antimicrobial Activity

Alkaloids solanine, solasodine, and β-solamarine isolated from Solanum dulcamara have shown antibacterial activity against S. aureus. This evidence is from in vitro studies; no human clinical trials of S. dulcamara-based antimicrobial preparations have been identified in the peer-reviewed literature.

4.5 Respiratory Conditions (Bronchitis, Asthma)

A traditional use in chronic bronchitis and asthma, in addition to eczema, rheumatism, and gout, has been described for S. dulcamara stipites. The EMA's assessment explicitly states that these other conditions (beyond eczema) cannot be considered suitable for a traditional use listing, and that a Community list entry cannot be recommended from available data for these indications. No controlled clinical studies in humans have been identified for respiratory indications.

5. Body Systems and Health Areas Associated with Bittersweet

Integumentary (skin): The most extensively documented area of traditional and regulatory-recognized use. Applications include chronic eczema, contact dermatitis, acne, furuncles, warts, and general skin eruptions. Because of antimicrobial effects, the German Commission E approved topically administered bittersweet nightshade for eczema, furuncles, acne, and warts.
Musculoskeletal: Traditionally used across a very wide range of ailments, with the main applications in treating rheumatism and as a purgative. Preparations were applied both internally (historically) and externally as poultices.
Nervous system / neurological (toxicological context): Reported signs of solanine toxicity include mydriasis, central nervous system depression, muscle tremors, incoordination, tachycardia or bradycardia, and respiratory difficulty. Neurologic signs result from direct neurotoxic effects of solanidine and acetylcholinesterase inhibition.
Cardiovascular: Extracts of the bark of Celastrus scandens are thought to be cardioactive. For S. dulcamara, cardiotonic effects were observed after oral administration of solasodine citrate in patients with rheumatic arthritis and ankylosing spondylitis.
Respiratory: Traditional use for chronic bronchitis and asthma is historically documented, though not recognized by current European regulatory monographs due to insufficient evidence.
Gastrointestinal: Combination herbal tea products have been registered for digestive complaints in some European national traditional-use frameworks.
Lymphatic / immune (C. scandens traditional use): Climbing bittersweet (Celastrus scandens) was employed by native North American Indian tribes; the root was diaphoretic, diuretic, and emetic, and was used as a folk remedy for chronic liver and skin ailments.

6. Dosage Forms and Reported Dosages

Dosages reported in authoritative historical and regulatory sources are as follows:

Extractum Dulcamarae Fluidum (Fluid Extract of Dulcamara): dosed at half to one dram, as recorded in Ellingwood's Eclectic Materia Medica.
Specific Medicine Dulcamara: dose of one-half to ten minims.
Topical adjuvant therapy of chronic eczemas: applied 3–5 times daily. EMA-registered preparations include a herbal tea combination product with 6.25% S. dulcamara, and capsules with 75 mg of S. dulcamara herbal substance.
An ethanolic extract (1:5, 30% ethanol) at 10 g per 100 g of final product has been marketed under a traditional use registration.
Under the EU herbal monograph, the infusion or decoction of comminuted herbal substance is applied cutaneously at room temperature to the affected area on a clean dressing.

Due to structural properties of the plant's alkaloids and other structurally similar substances, the herbal substance and preparations should not be used during pregnancy and lactation. The use in children and adolescents under 18 years of age is insufficiently documented.

7. Safety, Toxicology, and Interactions

7.1 Regulatory Classification

The stem (preparations and products thereof) is considered by the Council of Europe to be unfit for human consumption in any amount when taken internally. The Council of Europe report also indicates that the FDA classified the plant as an unsafe poisonous herb.

No toxicological information specific to the herbal substance or herbal preparations of S. dulcamara stipites is available from well-designed studies. Most toxicological studies have been performed on solanine and chaconine, steroid alkaloid glycosides present in Solanum tuberosum (potato) but not reported as major components in S. dulcamara stipites.

7.2 Toxic Principles and Mechanisms

The toxic principle of Solanum dulcamara is the steroidal glycoalkaloid solanine. Following ingestion, solanine is poorly absorbed from the gastrointestinal tract, causing local irritation and clinical signs of hypersalivation, vomiting, diarrhea, and ileus. In the GI tract, solanine is also hydrolyzed to solanidine, which is absorbed and produces a systemic toxidrome of neurologic, cardiovascular, and respiratory signs.

Solanine poisoning is primarily displayed by gastrointestinal and neurological disorders. Symptoms include nausea, diarrhea, vomiting, stomach cramps, burning of the throat, cardiac dysrhythmia, nightmares, headache, dizziness, itching, eczema, thyroid problems, and inflammation and pain in the joints. Cell membrane disruption is likely the cause of many symptoms, including burning sensations in the mouth, nausea, vomiting, abdominal cramps, diarrhea, internal hemorrhaging, and stomach lesions.

7.3 Variability of Toxicity with Plant Part and Ripeness

All parts of the bittersweet plant contain a mixture of steroidal glycoalkaloids often referred to collectively as "solanine." The alkaloids are degraded during the maturation of the fleshy fruit, which makes the berries more attractive food for birds. However, the ripe berries should not be regarded as safe to consume as they have been known to cause poisoning.

The toxicity of S. dulcamara berries was studied by gavaging mice with lyophilized berries ripened and unripened at various times of year. Mice receiving unripened fruit from early in the season had gastrointestinal tissue changes consistent with solanine toxicity, while animals dosed with unripened fruit from later in the year showed behavioral signs suggestive of solanine toxicity without gastrointestinal lesions.

7.4 Documented Human Poisoning Cases

A fatal case of solanine toxicity was reported in 1948, and the causative agent was identified as Solanum dulcamara (woody nightshade).

A published case report describes a large nightshade ingestion in a 4-year-old girl who presented to the emergency department in acute anticholinergic crisis. The child was given 0.2 mg of intravenous physostigmine (0.02 mg/kg); within 50 minutes, the patient received two additional equal doses with complete resolution of symptoms. After 36 hours of observation, the child was discharged. Analysis of the suspect berries revealed sterols consistent with solanine, and this case represented a unique presentation of woody nightshade poisoning with anticholinergic crisis responding to physostigmine.

A historical 1851 case report describes a 40-year-old man who, while using a decoction of dulcamara stalks for a cough, consumed a very large amount. By evening he was suddenly seized with numbness in his limbs, pains in his knees and elbows, dryness of the throat, and paralysis of the tongue. These symptoms increased over three to four hours so that he could scarcely move either his limbs or tongue. The head remained unaffected, consciousness was unimpaired, the pulse was quiet but small and rather hard, and breathing was regular, without nausea or vomiting.

7.5 Allergy and Dermatological Sensitization

A paper in Contact Dermatitis (2016) reviewed topically used European herbal medicinal products, including S. dulcamara, for contact dermatitis as an adverse reaction. There have only been records of medicinal use for adults, not children, and it is possible to be allergic to Solanum dulcamara; medicinal use is not advised in those cases.

7.6 Toxicity of Celastrus scandens

The fruits of Celastrus scandens are poisonous to humans when ingested, but are favorites of birds. The roots were used by Native Americans and pioneers to induce vomiting, to treat venereal disease, and to treat symptoms of tuberculosis — indicating an awareness of the plant's biological potency. Many plants in the Celastrus genus contain compounds of interest for their antitumour activity.

8. Distinction from Related Plants

Medieval herbalists referred to S. dulcamara as "woody nightshade" to distinguish it from its relative, "deadly nightshade" (Atropa belladonna). The two plants share the Solanaceae family and superficially similar berries but differ substantially in their toxic alkaloid profiles: atropine predominates in Atropa belladonna, while solanine is the primary toxic principle in S. dulcamara.

Bittersweet nightshade (Solanum dulcamara) may be confused with Asiatic bittersweet (Celastrus orbiculatus), which is also an invasive species. Additionally, the common name "bittersweet" may be applied interchangeably to S. dulcamara, Celastrus scandens, and C. orbiculatus depending on the regional and cultural context.

9. Summary of Evidence Strength

Topical use for eczema (S. dulcamara stem): Supported by traditional use recognized under German Commission E and the EU herbal monograph. Open observational study data suggest symptomatic improvement. No adequately controlled clinical trials exist. Evidence level: Traditional use / low-quality clinical observational data.
Anti-inflammatory / antirheumatic use: Well-documented historically. Preclinical (in vitro) evidence supports plausible mechanisms involving saponin-class and alkaloid compounds. No randomized controlled clinical trial data available for S. dulcamara specifically.
Antimicrobial activity: Demonstrated in vitro against S. aureus, E. coli, and antifungal targets. No human clinical trial data.
Anticancer properties: Preclinical in vitro and animal data only. Not translatable to clinical recommendations at this time.
Respiratory conditions: Traditional use documented; not recognized by EMA due to insufficient evidence. No clinical trial data.
All oral internal uses: Not recognized by current EU regulatory frameworks due to toxicity concerns.

References

Health Conditions

Health conditions that Bittersweet may help support.

No conditions available.

Body Systems

Body systems that Bittersweet may help support.

No body systems available.