2.1. Literature Search Strategy

Ethnobotanical studies reporting on MPs used for the treatment of evil eye illness in Ethiopia were identified using international scientific databases, such as PubMed, Science Direct, Web of Science, Scopus, and Google Scholar. Other related websites and PhD dissertation research reports were searched for using Google search engines and university websites.

The key terms used to address the expected objectives were “evil eye illness,” “evil eye,” “medicinal plants,” “traditional medicinal plants,” “indigenous knowledge,” “ethnobotany,” “ethnobotanical study,” and “ethnomedicine.” The search terms were used separately and in combination with Boolean operators such as “OR” or “AND”.

2.2. Inclusion Criteria

The inclusion criteria were published and unpublished ethnobotanical surveys reporting MPs related to evil eye illnesses during any period in Ethiopia. The inclusion criteria were restricted to original research articles published in English, which were studied in all parts of Ethiopia. Missing information in some studies (local names, family names, and growth habits of the plants) and misspelled botanical names were retrieved from the Google search engine, botanical databases (Natural Database for Africa Version 2.0, Royal Botanical Garden [Kew], World Flora Online), and Flora of Ethiopia and Eritrea, after which correction/rephrasing was performed.

2.3. Exclusion Criteria

Articles lacking basic ethnobotanical information (scientific name, parts used, and route of administration), study areas, or ethnobotanical studies that did not report information on the MPs used to treat the illness were excluded. In addition, studies that included only MPs for livestock usage, non–open access articles, partially accessed (abstract only) articles, review articles, and articles from other countries were excluded.

2.4. Study Selection

First, literature screening of the extracted articles involved examining the titles and abstracts of relevant articles for inclusion. Full-text articles were subsequently evaluated using the inclusion and exclusion criteria. The article selection process in this systematic review included 53 studies (Figure 1).

2.5. Data Collection

A Microsoft Excel spreadsheet (Microsoft Corporation, United States) was used to collect data on the MP species used to treat acute eye illnesses. The collected data, including botanical name, plant family, local name, part used, growth habits, mode of preparation, and administration, were checked for completeness. A careful review of the articles was performed, and the data were captured using this tool.

2.6. Data Analysis

Descriptive statistical methods were used to summarize and analyze the data. The results are expressed as percentages and frequencies and are subsequently presented as tables, bar charts, and pie charts.

3.1. Ethnic Distribution of MPs

Ethnobotanical studies citing evil eye illnesses included 19 ethnic groups that were distributed throughout the country (Table 1). Considering that the country is home to more than 80 ethnic groups, the illness mentioned by nearly a quarter (23.75%) of the ethnic groups may be related to the low ethnobotanical study coverage. Additionally, respondents’ hesitation to mention evil eye illness as one of the ailments of the area treated by MPs may play a part in the lower ethnic representation.

3.2. Regional Distribution of MPs

The studies included in this review were conducted in seven regions of Ethiopia, out of the 11 regional states and 2 city administrations (Table 1). The highest proportion of studies was reported in the Oromia region (37.73%), followed by the Amhara (30.19%), and the Southern Nations and Nationalities People (SNNP) region (11.32%) (Figure 2). The regional distribution of the disease showed that this condition was common in several areas and that the locals used traditional healing methods to treat it.

Many MP species (134 plant species, 43.79%) have been reported from the Amhara region, followed by the Oromia (82 plant species, 26.79%) and Tigray (40 plant species, 13.07%) regions (Figure 3). The sum of the percentages was greater than 100%, as most MPs used to treat evil eye illnesses are common among regions.

More than 70% of MP species are distributed mainly in the Amhara and Oromia regions, which are among the largest in terms of area coverage and population size. Although diverse ethnic groups and cultural practices are found in the SNNP region, it is the fourth region in terms of distribution of MP species. This may be associated with the fact that only a few studies (six articles) were conducted on this topic compared to the large number of studies conducted in the Oromia and Amhara regions.

3.3. Diversity of MPs and Associated Indigenous Knowledge

In the 53 articles reviewed, a total of 146 MP species belonging to 65 botanical families were identified for the treatment of evil eye illnesses (Supporting Information (available here)). This assessment is a good indication of people’s deep indigenous knowledge, as it shows how they continue to use indigenous methods to treat evil eye illnesses caused by a wide variety of plant species in Ethiopia. In the supplemental material, each species of MP is described in depth along with its family, local name, habit, plant parts used, method of preparation, and route of administration.

Fabaceae (22 species) was the most highly represented family, followed by Asteraceae (13 species), Lamiaceae (7 species), Solanaceae (7 species), and Euphorbiaceae (6 species) (Figure 4). These findings are in agreement with those of other reviews [73–75] that showed that Fabaceae is the most represented family. This finding was also consistent with a study conducted in Spain, where Fabaceae and Lamiaceae were the most widely used plant-based rituals for the prevention and treatment of evil eye illnesses [76].

It was found that, in the best-represented family, Fabaceae, which hosts 22 MP species used to treat evil eye illness, biosynthetic pathways produce flavonoids, terpenoids, and alkaloids as secondary metabolites [77–79]. Whether these secondary metabolites play a role in the treatment of this illness requires further investigation.

The most frequently cited species were Carissa spinarum (22), followed by Withania somnifera (17), Ruta chalepensis (14), Allium sativum (10), and Capparis tomentosa (10 citations each), as shown in Figure 5. These findings demonstrate that the therapeutic plants indicated above are regarded by the local people as the most effective means of treating evil eye illnesses. On the other hand, the mention of 100 species only once in the reviewed studies showed a wide range of indigenous knowledge exercised to cure ailments (Supporting Information).

These findings agree with those of previous studies in which Carissa spinarum [80], Allium sativum [76, 81], and Ruta chalepensis [76, 82] were used to treat illnesses in various parts of the world. Gonzalez et al. [76] argued that aromatic plants are commonly used to protect individuals from evil eye illnesses. Of the five most frequently cited plant species, Withania somnifera, Ruta chalepensis, and Allium sativum were categorized as aromatic plants, Carissa spinarum as an incense plant, and Capparis tomentosa as a MP.

3.4. Habits of the MPs

Assessment of the habits of the MPs used for the treatment of evil eye illness revealed that shrubs constituted the highest fraction, with 60 species (41%), followed by herbs with 45 species (31%), and trees with 34 species (23%) (Figure 6).

Approximately a quarter of the habitat was composed of shrubs and herbs (72%). Therefore, employing more shrubs and herbs could be advantageous because shrubs may be found throughout the year and herbs can be easily cultivated around homesteads. In addition, herbs and shrubs take less time to grow than do trees. However, herbs may be inaccessible during some seasons, particularly if wild sources are used [39, 49]. Several scholars have also reported herbs and shrubs as the most commonly used growth habits for the management of various human and animal ailments in Ethiopia [52, 53, 73, 83].

3.5. Utilized Parts of MPs

In this review, several parts of MP species have been reported to be able to treat acute eye illnesses. Roots were the most frequently used (75 citations, 37.13%), followed by leaves (46 citations, 22.77%), and a combination of roots and leaves (15 citations, 7.43%), whereas fruits, seeds, shoots, bulbs, latexes, and flowers were rarely used (Table 2). This review supports the findings of Lulekal et al. [84] and Kefalew et al. [85], who reported that roots are among the most commonly used plant parts in remedy preparations for various disorders in Ethiopia.

One of the advantages of using roots for the treatment of evil eye illness is that fresh roots can be easily harvested throughout the year, as they remain underground even during long dry seasons [49]. However, the extensive use of roots for the treatment of the evil eye may affect the longevity of the plant itself, as has been reported in the literature through the use of roots for the preparation of medications that may endanger MPs [86].

3.6. Remedy Preparations

Most of the reviewed articles reported that traditional herbal medicine practitioners usually combine different plant species when preparing herbal medicines for the treatment of eye illnesses. The synergistic interactions that occur among the different phytochemicals in mixed plants may result in increased efficacy. Fumigation is the most common method used for herbal medicine preparation. Others included decoction, infusions, drying, pounding into powder, chewing, and steaming.

3.7. Routes of Administration of Herbal Remedies

Herbal treatments for evil eye illnesses were delivered nasally (97 citations, 35.14%), dermally (63 citations, 22.83%), or orally (52 citations, 18.84%) (Figure 7). As evil eye is a mental disorder, this review agrees with the MP review on common mental illness in Ethiopia, which states that inhalation is a common route of administration [75].

When using the nasal delivery method, the substance is often smelled rather than directly injected into the nostril. Dermal administration involves tying the neck or arm, smoking the entire body by putting it in fire, brushing the body, or taking a shower while using a decoction. The remedies were also chewed and consumed immediately after collection, or following the first crushing or pounding. The common topical means of administration (nasal and dermal) mentioned in this review may be preferable because they have minimal toxicity and are the simplest and most convenient route of administration.