Dermatology

Garlic burn injuries- a systematic review of reported cases

a b s t r a c t

Medicinal plants have many beneficial effects on human health. Garlic (Allium sativum, Alliaceae) is one of the most famous herbal species, used for various diseases and conditions. Unfortunately, garlic is also associated with adverse effects, including cutaneous manifestations. In this review, burn injuries caused by application of raw garlic are reported. Searching through PubMed, Google Scholar and ResearchGate, a total of 32 articles with 39 patients were found. Demographics of patients, reasons for garlic use, details on garlic application, as well as description of burns and its treatment are thoroughly described and discussed. In most of the cases, garlic caused Second-degree burns, although some circumstances can cause formation of necrotic tissue. Various body parts were affected, legs being most common. The chemistry of garlic is also presented, with focus on volatile or- ganic sulfur compounds, which also seem to be responsible for burns formation. Treatment of garlic burns was mainly symptomatic, and various types of drugs were used. Although not commonly expected, garlic should be taken into consideration as causative agents of burns by treating doctors, and patients should be advised against application of fresh garlic onto skin and mucosa.

(C) 2021

  1. Introduction

A burn represents an injury caused by physical, electrical, biological or Chemical agents [1]. Although less frequently reported, insects, jelly- fish, fish, frogs and some plants are also recorded as causative agents of burns [2]. Probably seen as least harmful, and even used in treatment of burns caused by other types of agents (usually thermal) [3], plants still have the potential to cause burns themselves. Recorded cases report of burns caused by pepper (Piper spp., Piperaceae) [4], mustard (Sinapis spp., Brassicaceae) [5], fig (Ficus carica, Moraceae), walnut (Juglans regia, Juglandaceae) [6] and corn buttercup (Ranunculus arvensis, Ranunculaceae) [7].

Garlic (Allium sativum L., Alliaceae) is one of the most recognized medicinal plants, used since ancient times. Modern researches are fo- cused on its effects in cancer prevention, immunomodulatory and anti- oxidant properties [8,9]. Clinical data confirmed its effectiveness in application in hypertension and hyperlipidemia treatment and in pre- vention of atherosclerotic vascular changes [10].

Unfortunately, garlic is also associated with numerous adverse effects including odor, Allergic reactions (allergic Contact dermatitis, generalized urticaria, angioedema, pemphigus and anaphylactic re- action), as well as photoallergy, gastrointestinal complaints and

* Corresponding author.

E-mail addresses: [email protected] (M. Hitl), [email protected] (N. Kladar), [email protected] (N. Gavaric),

[email protected] (B. Srdenovic Conic), [email protected] (B. Bozin).

hypocoagulation effect [11]. Although it is most frequently taken per- orally, in traditional medicine, garlic can sometimes be applied topically. This type of application can result in another adverse effect, manifested as chemical- garlic burns. The scientific literature only scarcely reports of this type of injuries, although it can be presumed, based on world- wide usage of garlic, that these burns may represent an unidentified threat in inadequate types of treatment. The aim of this review is to present reported cases of garlic burns and to discuss application details.

  1. Methods
    1. General overview

This review is in accordance with Preferred Reporting Items for Sys- temic Reviews and Meta-Analysis (PRISMA) guidelines [12].

    1. Search strategy

The search for reported cases was performed in PubMed database, with additional searches in Google Scholar and ResearchGate sites. The search was performed separately by M.H and N.K., after which the articles were evaluated and the duplicates were removed. The search was performed combinations of words “garlic” or “Allium sativum” with “burn” or “burns”. Additionally, retrieved articles’ references were thoroughly checked for additional references. After search in En- glish, additional checking was performed combining Spanish terms “ajo” and “quemadura” or “quemado”. The additional searches were performed by M.H., N.G. and B.S.C.

https://doi.org/10.1016/j.ajem.2021.01.039

0735-6757/(C) 2021

Fig. 1. Flow chart of article Selection process, according to PRISMA guidelines.

    1. Inclusion and exclusion criteria

As this review aimed toward garlic burns, only the case reports where the injury was classified as garlic burn by the treating doctor or dentist were included. The type of articles included were case report or articles reporting several cases of burns. Other types of articles, pri- marily reviews of similar topics or letters to the editor and commentar- ies in journals were excluded. The search had no restriction concerning

date of published articles. Concerning the patients, this article included both genders, all age groups and ethnicities.

    1. Data extraction and analysis

After retrieving articles, relevant data were extracted from the arti- cles: age and sex of patient, reason of garlic use, detail on garlic applica- tion, location and characteristics of burn, treatment and final outcome.

Data extraction was performed by M.H. and N.K. Data were presented descriptively, in details; due to some data lacking in some papers, it was not possible to perform further statistical analysis. Final revision of research process was performed by B.B.

  1. Results and discussion
    1. Search results

Total of 32 papers were found, including 39 reported cases of garlic burns. Papers in English were originally included. However, two addi- tional case reports were encountered in Danish and Chinese ([13,14], respectively), but only the data from abstracts were included in this re- view. The flowchart of article selection process is given in Fig. 1.

    1. Reported cases

After careful investigation of 39 patients with garlic burns, the rele- vant data were extracted from case reports [4,13-43]. The main findings are presented in Table 1; detailed data from all reported cases are pre- sented in Supplementary Table 1.

    1. The patients

Among the patients, sex distribution was nearly equal, with 18 male and 21 female patients. However, age of the patients was quite diverse, from youngest being 3-months-old baby girl [20], to 80-year-old woman [28]. In cases of burns reported in babies and small children, child protective service or social workers were informed about these in- juries, in order to exclude child abuse [36,42].

The reasons for garlic application were different. In general, patient can be divided into two groups: ones unaware of garlic potential to cause harmful effects and others aware of this. The second group could be further divided onto two subgroups, first one using this for some therapeutic aim, and those “abusing” garlic. Patients unaware of potential effects of garlic, used this herb in order to treat some underly- ing condition, with pain being the most common [6,13,23,25,26,30, 32,34,37,40,43], but also for some skin conditions [19,33,38], respiratory diseases [21,31,36], fever and cold [15,16,20,42], as well as stress re- liever [27]. The second group of patients, using garlic purposely for its chemical/abrasive effect, applied it for removal of skin warts [29,43], acne [39], black spots [14], nail infection [41], tattoo [35] or foot erosion [17]. However, it is possible that this group of patients was unaware that garlic application can also cause adverse effect in a form of Burn injury, besides achieving the aim (e.g. wart or tattoo removal) it was originally used for. Finally, one group of patients was aware of potential harmful effects of garlic and used it purposely in order to self-inflict injuries and be exempted from work or military duty [22,24].

The source of information was different in various cases, as advice to apply garlic came from a relative/family member [16,23,37,40], a friend [28,39], a herbal healer/naturopathic physician [15,21,26] or from an in- ternet source [29,32,36,38], and it is interesting that a significant part of all detected patients followed an encountered advice. The tendency of more frequent appearance of new cases (20 cases in last 10 years as op- posed to 19 cases in period of 22 years since the first reported case in 1987) could possibly be explained by new ways of distribution of infor- mation. Interestingly, no patient received the advice from a medical doctor or a dentist. One patient even stated that this is his second use of topical garlic paste; positive previous experience encouraged him to use it again [40].

    1. Location of burns

Detailed anatomical positions of garlic burns reported in cases are given in Supplementary Table 1. Graphical illustration of burns is repre- sented on a human body scheme (Fig. 2).

Most of the recorded cases are located on patients’ legs (20), head (9), arms (6), thorax and abdomen (4). The site of garlic placement is primarily determined by location of treated condition. However, acces- sibility of treated area is also important, explaining why some areas were frequently affected, while others were not recorded. To best of our knowledge, there were no recorded cases of garlic burns to genital organs. One case reported vaginal application of incised garlic clove, as patient was self-medicating genital infection. No garlic burn was re- corded in this case [44].

    1. Characteristics of burns

Nearly all of the reported cases classified reported garlic burns as second degree, partial thickness burns. In most of the cases, erythema and vesicobullous changes are reported, being consistent with penetra- tion into dermis, causing the outer barrier loss and interstitial fluid leaking [45].

Some of the cases reported presence of necrotic tissue. The first one, necrotic ulcer reported in 6-year-old girl could possibly be explained by young age of patient and with foot being the affected area, as well as with prolonged use of garlic, during two whole days [17]. In the second case, necrotic changes are probably consequences of oral application of garlic, during several days [37]. Another case reported results of per- formed skin biopsy, where focal separation of epidermis and dermis was seen; presumably, necrotic changes could be consequences of 18- h exposure [18].

Later consequences of burns may include cellulitis, wound infec- tions, sepsis and scarring complications [46]. One patient developed subsequent cellulitis in both feet after garlic application, possibly due to underlying condition, diabetic neuropathy [23]. Another patient de- veloped an infection with Pseudomonas aeruginosa, later successfully treated with antibiotics (although infection prolonged Healing process) [40]. Several papers reported scars after healing, which could be ex- plained with young age of patient [16], long time of garlic exposure [18], or burns being on patient’s face [38,39].

The size of burns corresponds with the size of area directly treated with garlic. In reported cases, the burn size varies from those of 1 cm in diameter, up to burns affecting approximately 10% of total body sur- face area. Besides the size and degree, the shape and borders of the burn can have a role in differential diagnosis of garlic burns. In one case, her- pes zoster was falsely diagnosed; however, streaky appearance was sus- picious to doctor and further led to additional questioning, finally revealing the garlic as causative agent of the burn [18]. It is pointed out that burn borders are sharp [22,24,29,38]. Two reported papers stated that patients claimed burns to be caused by hot coffee; however, lack of dripping signs and lack of sharp borders were inconsistent with these diagnoses [22,24]. In case of the two patients, it was easy to sug- gest garlic as culprit, as the characteristic smell was still present [24]. Two cases of oral mucosa burns pointed out the similarity to burns

Table 1

Summary of reported cases of garlic burns.

  • A total of 32 articles were found
  • 39 reported patients — sex: 21 female, 18 male; age: from 3 months to 80 years (ethnicity, religion or geographical distribution were not reported in this review)
  • Some of the reasons for garlic use: treatment of an underlying condition, use of garlic’s abrasive effects, abuse in order to self-inflict injuries
  • The use of garlic was frequently associated with additional

wrappings/cloths/bandages etc.; only fresh garlic was used

  • Most of the cases resulted in second degree burns
  • The burns affected the patients’ legs (20 reported burns), head (9), arms (6), thorax and abdomen (4)
  • Treatment included the use of antibiotics, antiseptics, anesthetics, antihistamines, topical steroids, panthenol and other vitamins as well as var- ious analgesics

Fig. 2. Anatomical location of reported garlic burns. Arrow pointing from last name of author(s) to two or more locations is a single reported case, with burns in two or more places.

caused by aspirin tablets, sometimes miss-used orally for analgetic pur- poses [25,37]. These cases suggest that good communication between patient and treating doctor is needed, in order to obtain complete pa- tient history and to adequately diagnose the caused injury.

Friedman et al. (2006) suggested that average time needed for burn development is 6 to 8 h in children, and more in adults [24]. In most of the reported cases, this is consistent with suggested time, although burns appeared in period of approximately 1 h are also reported [28,34]. Prolonged uses, over two days [17,19] or during several days/

nights [25,37], or even for several hours during 4 weeks [41], usually re- sulted in burns with necrosis, as previously described.

    1. The chemistry of garlic compounds and garlic burns mechanism

Species of genus Allium include garlic, onion, chives and leek. Charac- teristic odor as well as biological and pharmacological properties are at- tributed to organosulfur compounds present in these plants. In case of intact garlic cloves, compound alliin and enzyme allinase are stored

Image of Fig. 3

Fig. 3. Chemistry of garlic. Inactive compound alliin (blue) and its enzyme (yellow) are stored separately. After destruction of garlic tissue, allicin (green) is formed.

separately, and they are stable in dry and undamaged tissue. After me- chanical destruction (crushing, grounding, incising), these precursors form allicin. This compound is presumed as active principle; however, it is quite unstable, especially to heat. Further reactions lead to forma- tion of various organosulfur compounds, including diallyldisulfide (Fig. 3) [47].

In nearly all reported cases, patients emphasized that the garlic was fresh and that some type of mechanical destruction of cloves was per- formed, which is in accordance with previously described chemistry. The level of garlic tissue destruction corresponds with amount of formed allicin, as more allin and its enzyme are brought to reaction. Bearing this is mind, it is completely understandable that allicin amount is and will be different in each different case; thus, it is not possible to quantify it and compare individual cases.

It is also important to point out that released garlic compounds are highly volatile [47,48]. Patients seemed to be aware of this fact, as most of then used some sort of wrap, bandage, occlusive dressing or even just a cloth or headscarf, in order to fix garlic in treated location and possibly to enhance the effect of sulfur compounds. This tight fixa- tion allows created allicin and other compounds to quickly react with macromolecules. It is presumed that formation of disulfide bond be- tween sulfur group of allicin and thiol groups of enzymes and other structures is responsible for garlic burns [43]. The addition of table salt in two cases [33,35] possibly worsened the given situation due to salabrasion effects on epidermis [35].

    1. Allergic implications?

The potential of garlic to cause allergic reaction is well documented and some of them are previously mentioned. Allergic contact dermatitis is often found as occupational allergy in cooks, housewives and others in frequent contact with garlic [11,49]. Main allergens in garlic are diallyldisulfide, allylpropyldisulfide and allicin. These compounds are electrophiles in nature, with potential to interact with nucleophilic

groups in proteins, eventually forming a hapten-protein conjugate, act- ing as allergen [50]. Enzyme allinase can also act as strong allergen [51]. So, is it a burn or an allergy? In some of the cases, Patch testing [15] or specific IgE test [18,21] were performed; as these test came out neg- ative, allergy was excluded. Other case considered it unnecessary, as child had no previous contact with garlic [16]. As previously stated, sul- fur in garlic’s active compounds seems to be the responsible for both ir- ritant chemical effects and for allergic reactions [16]. Besides this, it is necessary to consider patients’ predispositions for these allergic condi- tions. It was demonstrated that garlic has the potential to induce acantholysis, although this process was noticed only in certain skin do- nors, suggesting that individual susceptibility has an important role in condition development [48]. Based on previously said, it can be con- cluded that garlic has potential allergens and individual factors may contribute to susceptibility to garlic burns, but not all garlic burns can

be explained by allergy or individual susceptibility.

    1. Treatment

Treating doctors had various approaches to burn treatment. In most of the cases, wound debridement, cleaning and irrigation were per- formed. Doctors also applied various types of antibiotics, usually topical, with silver sulfadiazine being the most common, but also bacitracin, mupirocin and chloramphenicol were used. Current suggestion for use of these antibiotics state that they should be used for a Short period of time, due to impairment of reepithelization process [45]. Other used drugs include: anesthetics- benzocaine [25], antiseptics- chlorhexidine [6,25,34] and povidone iodine [14], antihistaminics [31], topical steroids [24,31], panthenol and other vitamins [28] as well as various analgetics. Various types of dressings were also advised and applied to patients, where dressings which maintain a moist environment are currently rec- ommended for use [45]. Only one reported case required skin transplant due to long period of time (4 weeks) during which a wound had not healed [13].

  1. Conclusion

Fresh garlic has the potential to cause burns when applied to skin and mucosa. Cases differ among each other as amount of garlic, details of application and characteristics of patients can vary widely. Most com- monly, it causes second degree burn which requires standard treatment and leaves no major consequences. Still, treating doctor should be aware of garlic as potential causative agent, in order to be able to diag- nose and treat condition adequately. Patients should be educated that “herbal” is not equal with “safe” and should be advised against inade- quate use of raw garlic in order to prevent injuries.

Acknowledgements

This work was supported by The Ministry of Education, Science and Technological Development, Republic of Serbia (grant number 451-03- 68/2020-14/200114).

Declaration of Competing Interest

The authors declare that they have no conflict of interests.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2021.01.039.

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