Poison or Remedy? Case Reports on Selected Plants

Apium graveolens L. (Apiaceae; formerly Umbelliferae) is distributed from Europe to the Western Himalayas and from Micronesia to North Africa. The plant is called “celery” and is commonly consumed as a vegetable, also used as medicine, poison, and animal food. The plant has many pharmacological activities such as antioxidant, antimicrobial, hypocholesterolemic, cardiotonic, antidiabetic, antiulcer, hepatoprotective, antiplatelet, larvicidal, anti-spasmolytic, anti-inflammatory, anticancer, analgesic and anti-infertility. However, many important health problems have also been reported with the use of celery. Case reports indicate that important conditions like anaphylactic shock, food-dependent exercise-induced anaphylaxis, hyperthyroidism, bipolar disorder, phototoxicity, and acute irritant contact dermatitis may occur due to the use of celery.

The genus Cinnamomum Schaeff. (Lauraceae) has more than 250 species, which consist of aromatic trees and shrubs, and only a few are used for the production of popular bioactive food ingredients cinnamon and cassia. They are made up of dried stem bark layers and are presented as quills or powders in the market. Essential oils from different parts of the plant are also used in the food, cosmetic and pharmaceutical industries. Traditional uses of this beneficial spice with respect to medicine include the treatment of respiratory and gynecological disorders, and digestive complaints including bloating, flatulence, and mild diarrhoea. Many recent studies have focused on different pharmacological activities of Cinnamon and Cassia such as antiinflammatory, antimicrobial, anticancer, antioxidant, anti-hyperlipidemic, and antidiabetic activities.

Clinical benefits have contributed to cinnamon consumption; however, cinnamon may have some adverse effects, as well. Coumarin, a cinnamon component, is hepatotoxic and carcinogenic. It was discovered that cinnamaldehyde may disrupt respiratory homeostasis and sensitize skin. The safe daily cinnamon intake in Europe is 0.1 mg/kg/day. Contact dermatitis and chronic mucositis associated with cinnamon hypersensitivity were also observed.

Datura L. and Brugmansia Pers. are two genera of the Solanaceae family, both known by the name Angel’s Trumpet. Solanaceae family is well-known for its economic, ornamental, and medicinal plants that contain tropane alkaloids, and species of these two genera have been used since ancient times for their various activities. They also have illicit usage due to their hallucinogenic and euphoric effects, especially in young people. These plants are toxic due to atropine and scopolamine alkaloids that they contain in addition to accidental poisonings that are seen with the usage of members of these two genera. They are also involved in many hospitalizations and criminal cases such as rapes and robberies.

Natural products, especially medicinal plants, play substantial roles in the management of health-related problems. Before the prevalence of modern medicine, phytotherapy was the predominant form of primary health care all over the world. However, it is well known that plants can do more harm than good if not handled with care. Many serious adverse effects that can result in death have occurred due to the misuse of unidentified plants and mindless usage. Gloriosa and Colchicum species are important medicinal plants that have diverse biological effects, and they contain alkaloids such as colchicine and their derivatives as the main active principles. Plants are used for medicinal purposes in traditional systems, particularly due to their antiinflammatory, tonic, abortifacient, anthelminthic, analgesic, and laxative features. In addition to the important benefits of these two Colchicaceae plants, toxic effects due to their poisonous alkaloids have also been determined. In this study, an insight into the medicinal usage of G. superba and C. autumnale together with their toxicity in terms of case reports will be provided.

Glycyrrhiza glabra L., commonly known as licorice, is a prominent medicinal plant of the Fabaceae family, recognised for its extensive therapeutic applications in various traditional systems of medicine. Licorice, including the roots and rhizomes of Glycyrrhiza spp., is known not only for its pharmacological properties but also for its use in cosmetics as a depigmentation agent and in foods as a flavouring and sweetener. Glycyrrhiza glabra is one of the main representatives of the drug “licorice,” whose main chemical constituents are triterpene saponins, flavonoids, and phenolic compounds. Licorice is cultivated throughout the world and is used in both conventional and traditional medicine.

The rhizomes and roots of licorice are used medicinally, either alone or in combination with other herbs, to treat a variety of conditions including stomach ulcers, hyperdipsia, flatulence, and colic, aside from respiratory conditions such as coughs, asthma, tonsillitis, and sore throats. Despite its long tradition and broad use, licorice is not without risk. A substantial number of side effects have been reported, predominantly with long-term use. Chronic or excessive use can lead to serious side effects, including hypokalemia, hypertension, and, in extreme cases, fatal cardiac events. This chapter also presents case reports that exemplify these adverse effects and highlight the importance of the cautious use of licorice in clinical practice. The findings suggest that while Glycyrrhiza glabra remains a valuable medicinal resource, its potential for toxicity requires careful administration and monitoring.

Hedera helix L., common ivy is a popular ornamental and medicinal plant that is generally known for its usages against respiratory tract diseases, and irritating cough. It also has various biological activities such as bronchospasmolytic, antileishmanial, antitumor, anti-inflammatory, antitrypanosomal, antimutagenic, molluscicidal, antioxidant, antimicrobial, analgesic, anthelmintic and antithrombin activities. The main active compounds responsible for these biological activities are triterpenic saponins. Common ivy is a widespread plant that contains strong irritants like polyacetylene compounds, falcarinol, and didehydrofalcarinol, which are powerful irritants that cause severe contact eczema in patients generally via dermal contact. It occurs mainly in spring when ivy grows rapidly and usually when it is pruned. Typical symptoms of ivy dermatitis are linear and vesicular eczema, allergic contact dermatitis on the hands, lateral parts of fingers, fingertips and forearms, neck, face, trunk, and lower legs. Additionally, commercial herbal supplements containing H. helix for respiratory tract diseases may cause unexpected side effects for children like moderate angular cheilitis and diaper dermatitis, mild vomiting, acute tubulointerstitial nephritis, and mild nausea. Especially allergic people are recommended to be careful when using the H. helix plant and the products prepared from the plant. 

Heracleum L. genus has been used for many years for medicinal purposes and also as food and spice. Heracleum species contain flavonoids, coumarins, lignans, sterols, and volatile compounds, and due to these secondary metabolites, members of the genus have many biological activities such as analgesic, anti-diabetic, vasodilator, and cytotoxic activities. Heracleum species are considered a public health hazard since they cause phototoxic reactions when skin is exposed to the sap and then UV rays. Compounds responsible for this effect in Heracleum species are furanocoumarins such as sphondin, bergapten, and pimpinellin. When we search the case reports found in the literature, we can see that the species responsible for toxicity are usually identified as H. mantegazzianum Sommier & Levier, H. laciniatum Desf. (Syn. H. sphondylium subsp. sphondylium), and H. sphondylium L. The most common adverse effects are blisters, skin burns, and erythema. 

In this present review work, nutmeg and mace from Myristica fragrans Houtt. were elaborated associated with their risks in use. Nutmeg, as a spice and medicinal preparation, is known and documented to be used as a carminative, expectorant, and analgesic and also used in infants. However, due to potential toxicological issues, as in the case reports, the use should be limited. Especially the narcotic effect, when consumed excessively, is associated with its components, myristicin and elemicin in particular. It is necessary to limit the use of nutmeg and be aware of potential drug interactions as well.

Nerium oleander L. is an evergreen shrub belonging to the Apocynaceae family. This species contains toxic cardiac glycosides and has been historically known as a poisonous plant. Oleander has been used in ethnomedicine for its cardiotonic, diaphoretic, diuretic, anticancer, antibacterial, antifungal, and expectorant effects.

Peganum harmala L. is a member of the Zygophyllaceae family, commonly known as ‘Harmal’, which grows spontaneously in Southeast Morocco, North Africa, and the Middle East, where its seeds are used traditionally for various purposes. Traditionally, in Anatolia, various shaped amulets are made by arranging the dried fruits on a decorative rope. The seed incense is commonly used against the evil eye, stressful conditions, and psychological disorders. Peganum seed and root preparations are reported for their antipyretic, narcotic, sedative, diaphoretic, and menstrual activities, usually used internally as an infusion (2-5%). The incense of P. harmala seeds is used against hemorrhoids. In addition to its traditional uses, there are several in vitro and in vivo studies on the antioxidant, antinociceptive, antimicrobial, antifungal, antidiabetic, antidepressant, and antitumor activities, among other biological activities. It is documented that itsintended use as an abortifacient and emmenagogue may cause serious consequences and complications. Consuming P. harmala preparations at high concentrations may cause serious damage and life-threatening situations due to the secondary metabolites, harmane alkaloids in particular, which is reviewed in this chapter with current literature data. 

Rhododendron L. is one of the largest dicotyledonous plant genera in the world, represented by more than 1.000 species, most of which grow naturally in the Northern Hemisphere. Many species and cultivars are also grown commercially, as rhododendrons are widely used in landscaping in many parts of the world due to their overall showy appearance and beautiful flowers. The first written information about these plants dates back to 401 BC and gives information about the toxicity of rhododendron honey. Rhododendron species and their products, such as honey, Labrador tea, edible flowers, and some medicines used in folk medicine, are known to cause poisoning cases due to human consumption. Some rhododendrons are also poisonous to grazing animals. Toxicological studies on Rhododendron species have addressed clinical observations and identified toxic components. Rhododendron and honey poisoning have been reported to be primarily associated with lipid-soluble grayanotoxins. These compounds affect sodium channels in cell membranes and cause a number of neurological, gastrointestinal, and cardiovascular dysfunctions. Grayanotoxins are found all over the plant, including flowers and nectar. Despite their toxic content and effects, rhododendrons and contaminated honey (mad honey) have been used in ancient systems of medicine, such as Traditional Chinese and Ayurvedic Medicines, as well as in European and North American Folk Medicine. However, mad honey is mostly consumed in Nepal and Türkiye as a recreational and traditional medicine. This review aims to present a comprehensive report on the toxicity of the Rhododendron genus after presenting the general botanical and ethnobotanical features.

Ricinus communis L. (Euphorbiaceae) is a medicinal plant known as castor oil plant and has highly toxic effects due to its ricin content. Root leaves and especially seeds of this plant, which has a wide distribution area in the world, are rich in terpenoids, phenolic compounds, and fatty acids. For this reason, the plant, used by the ancient people as a laxative for infections, inflammations, and toothache, has shown various biological activities. Antioxidant, anti-inflammatory, antimicrobial, and anticancer properties of the plant and its compounds have been determined in multiple studies. However, its seeds have toxic effects on humans and animals.