Scope, inclusion, and exclusion criteria

This review included studies on international travellers and migrants with voluntary and transient mobility. We included international tourists, backpackers, international students, business travellers and transient or seasonal migrant workers. Travellers and temporary migrants were analysed as a single conceptual category because they share similar adaptation challenges in unfamiliar environments, such as limited social capital, social positions, language difficulties, cultural differences, and barriers to healthcare access [19–21]. The synthesis was to identify and highlight commonalities across these populations rather than differences. Permanent migrants were excluded due to their long-term integration into destination health systems, which differs substantially from the temporary context of transient mobility [21]. Refugees and asylum seekers were also excluded because their health needs may be shaped by forced displacement and trauma, requiring distinct analytical frameworks [19].

A systematic search was conducted in MEDLINE, Embase, International Pharmaceutical Abstracts, PsycINFO, and CINAHL databases to find qualitative, multi-methods, and mixed-methods primary research articles focusing on self-care and travel without imposing language restrictions. Non-original research articles (non-peer-reviewed articles/preprints, posters, conference abstracts, protocols, book sections, book reviews, dissertations, letters to the editor, opinions, or commentaries) were excluded. All co-authors and a health science librarian developed the search strategy using keywords related to self-care and travel (S3 Appendix). Searches were initially performed on 5 October 2022 without limiting publication date and language, and updated on 30 October 2024 to capture records since inception.

Study selection and quality assessment

A literature search was conducted, followed by manual and automated deduplication using Covidence [22]. Twenty records were selected for initial pilot screening. Title and abstract screening of the remaining articles was conducted afterwards, followed by full-text screening. Discrepancies were discussed until a consensus was reached. All processes that indicate a change in the number of articles were noted on the PRISMA flow diagram [18]. The following data were extracted from each article and tabulated: first author, publication year, aim, population, geographical location, sample size, data collection methods, and data analysis methods.

Eligible articles were assessed for quality using the CEBM Critical Appraisal of Qualitative Studies sheet, which consists of eight questions with “Yes”, “No”, or “Unclear” response options [23]. The questions included the study rationale, the appropriateness of a qualitative approach, the sampling strategy, data collection methods, data analysis, the researcher’s position, whether the results made sense, a result-justified conclusion, and transferability of findings. The CEBM checklist does not specify exclusion thresholds; therefore, we adopted a conservative criterion, excluding studies with more than two ‘No’ responses to maintain methodological rigour. This pragmatic threshold was chosen because multiple negative responses indicate significant limitations in design or reporting. Each study was independently assessed, and discrepancies were resolved through consensus. Inter-rater reliability was supported by calibration exercises and documented decision logs.

Data synthesis

Meta-synthesis is a generic term for synthesising qualitative studies such as meta-ethnography, meta-aggregative review, meta-study, or thematic synthesis [17,24]. Quantitative findings from multi-methods and mixed-methods articles were excluded. We applied the thematic synthesis approach by Thomas and Harden [25] as it provides a clear step-by-step guide and allows for the integration of qualitative findings across diverse contexts and methodologies while preserving interpretive depth. The approach uses three stages for synthesising the data: line-by-line coding, grouping codes into one or more descriptive themes, and generating analytical themes. Coding was conducted line-by-line for all texts under the original study’s ‘results’ or ‘findings’ section [25]. For multi-methods and mixed-methods articles, the texts under the section that indicates the presentation of qualitative findings were subject to extraction. Codes were grouped into descriptive themes through an iterative process of comparison and refinement. Analytical themes were generated by interpreting relationships among descriptive themes in light of the review question and theoretical frameworks.

Coding reliability was ensured through a multi-step process. Each line of the text data from each article was coded according to its meaning and content, and descriptive themes were developed by inductively grouping codes into a hierarchical tree structure based on similarities and differences. A preliminary codebook was developed during pilot coding and refined iteratively as new codes emerged. Analytical themes were generated using descriptive themes to answer the review question. Discrepancies were discussed in detail to reach a consensus, considering the meaning behind each theme and its relevance to the research question. The descriptive and analytical themes were tabulated along with at least two supporting quotes from the original studies to enhance transparency. NVivo 13 was used for data management and theme development [26]. Formal inter-coder reliability statistics were not calculated, as thematic synthesis prioritises consensus-building over quantitative agreement. All coding decisions were reviewed collaboratively to ensure consistency.

During the synthesis process, the SCM served as a sensitising concept (background ideas that shape and influence how the research problem is approached) during coding and interpretation [12,27], ensuring theoretical integration beyond the mapping. The SCM constructed self-care in four dimensions using 32 existing theories, frameworks, and models [12]. Each dimension underscores different aspects of self-care, from personal actions to broader systemic and policy influences. The Self-Care Activities dimension focuses on individual activities and capabilities for self-care and includes the Seven Pillars of Self-Care [12,28]. The Self-Care Behaviour dimension addresses actions that support positive self-care behaviours and lifestyles. The Self-Care Context considers reliance on resources and their utilisation. The Self-Care Environment focuses on drivers and barriers to self-care within the broader fiscal and policy environment, along with cultural and social factors. Codes and descriptive themes were iteratively compared against the SCM dimensions during analysis.

Mapping to the self-care matrix

To map the meta-synthesis results with current theory in self-care, the SCM was employed [12]. A mapping procedure was developed to assess conceptual similarities between the meta-synthesis descriptive themes and the SCM’s dimensions and domains. The relationships were categorised into convergence, partial convergence, and lack of convergence. A relationship was convergent when one or more descriptive themes were similar to a dimension or domain. Partial convergence occurred when a descriptive theme related to more than a single dimension or domain. A lack of convergence occurred when a descriptive theme was unrelated to the SCM dimensions or domains. Discussions were made to address disagreements with consensus-building.

Reflexive statement

The research team comprised health professionals from different backgrounds, including pharmacy, medicine, nursing, and public health. All members were experienced in conducting qualitative meta-synthesis (collective experience = 23 years), qualitative or mixed-methods studies (collective experience = 80 years), and research in topics of self-care (collective experience = 73 years) and travel health (collective experience = 10 years). Most team members were well-travelled globally.

Study characteristics

Of the 2,394 articles retrieved after deduplication, 105 were assessed for eligibility (Fig 1), and 17 were included in the synthesis (Table 1).

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Table 1. Study characteristics.

https://doi.org/10.1371/journal.pone.0344437.t001

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Fig 1. PRISMA flow diagram.

https://doi.org/10.1371/journal.pone.0344437.g001

Two studies were conducted among tourists [33,43], and 15 were among the migrants [29–32,34–42,44,45] (Table 1). The articles reported self-care practices for skin diseases [29], dengue fever [43], malaria [39,45], unspecified fever [31], type-2 diabetes [36,40–42], and cardiovascular disease [33]. Five articles did not report specific health conditions [32,34,35,37,44]. Unless otherwise specified, this section’s term ‘travellers’ encompasses both international travellers and migrants. When assessed with the CEBM checklist, common risks for quality were the reporting of the researcher’s positionality (S4 Appendix). However, all identified studies met the quality threshold for meta-synthesis and were included for analysis.

Descriptive themes, analytical themes, and mapping to the Self-Care Matrix

We generated 21 descriptive themes (S5 Appendix) using an inductively developed codebook (S6 Appendix), considering travellers’ health statuses and strategies to maintain health conditions and cope with acute or chronic illness, such as relying on self-treatment and accessing health services at and outside the destination country. The sample of quotations from primary studies for theme generations was also presented in S5 Appendix. Descriptive themes varied from individual factors, such as hygiene practices, to broader social and environmental factors, such as stigma, legal status, and discrimination. We synthesised five analytical themes to answer the review question: self-care empowerment, mutual understanding of cultures, healthcare challenges and opportunities, preventive self-care, and facilitated self-care.

All descriptive themes, except social engagement, mapped to the SCM (Fig 2). Partial convergences were observed on three descriptive themes: self-care products and medicines, self-treatment, and adherence to treatment, which were linked to Self-Care Activities (Rational use of products and services), Self-Care Context, and Self-Care Environment dimensions of the SCM. Social Engagement did not converge with the Seven Pillars of Self-Care, which are part of the SCM’s Self-Care Activities dimension. This divergence is because it represents a relational determinant with social networks, i.e., social capital as a meta-contextual factor, rather than a discrete self-care activity.

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Fig 2. Meta-synthesis descriptive themes mapped to the Self-Care Matrix.

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Self-care empowerment

Voluntary international travellers tended to have some degree of preparation driven by knowledge and health literacy, but could miss some important matters. Travellers prioritised personal medicines and devices on the checklist, but attending pre-travel consultations appeared lacking [30,33]. Health insurance was essential, but only for those who could access and afford it [33,34,43]. Some travellers understood possible risks related to individual health and environmental situations, but sometimes did not understand the details [33,38,45]. Most often, travellers did not know the destination country’s healthcare system until they needed to access it [30,33–35,43]. Unfortunately, navigating the health system was not always easy, especially when social capital was deficient and other barriers were present [30,33–35].

Travellers needed self-care empowerment through community interventions and initiatives to overcome those gaps. Interventions and initiatives improved travellers’ knowledge, motivating them towards positive behaviour change and reducing layered barriers to healthcare access [38,39,41]. The involvement of community-based organisations and community figures, such as religious leaders, could improve the delivery and acceptance of interventions [38,41].

Mutual understanding of cultures

As foreigners in an unfamiliar environment, travellers felt at a disadvantage due to cultural differences. Language barriers were common, as well as major cultural barriers [29–31,33,34,36]. For example, travellers with limited language struggled to explain their problems to a health professional, which could deter them from future access [30,33]. Unpleasant feelings were reported when interacting with the locals, even when an interpreter was present [33,34]. Moreover, travellers may bring cultural practices and beliefs that are at odds with the destination country’s culture [30,35–37,40].

Many travellers understand that the benefits of travel include broadening their language and cultural horizons [33]. Some travellers were able to learn and adjust to the destination country’s culture [35]. Meanwhile, others wanted the destination country’s recognition of their cultural background, practices, and beliefs [34,36,40]. For instance, travellers suggested the integration of their languages into the destination country’s health services from translated information materials [36] to the provision of health professionals who can speak their languages [34]. Therefore, there was a need for mutual understanding of cultures, i.e., travellers wanted their cultures to be understood and accommodated, and they needed to understand the destination country’s culture in relation to self-care.

Healthcare challenges and opportunities

Travellers did not typically require daily access to the destination country’s healthcare services. However, when access was required, availability and accessibility were sometimes limited [30,33]. Despite language barriers, travellers often faced other challenges generated inside and outside the destination’s healthcare systems, such as stigma and discrimination, legal status, and financial and insurance constraints [29,31–34,36,38,41–43].

Travellers had different solutions to overcome those challenges, such as visiting other countries [34] or returning to their country of origin [29,34,44] to obtain care from more accessible health services. Some travellers rely on themselves, family, or other immediate circles, if any, which could delay seeking care [29,31,39,43,45]. Other travellers opted for unregulated resources, such as online marketplaces [44], the black market [29], or lay injectionists [31,37]. Therefore, there is a need to reduce travellers’ challenges in accessing formal healthcare to improve health outcomes.

Preventive self-care

Practising self-care to prevent unwanted health events or deterioration of pre-existing health conditions can maximise travel benefits. Preventative self-care practices reported by travellers included maintaining hygiene to prevent skin problems and preparing food [29,32], identifying foods and beverages they thought were healthy from the unhealthy, including traditional foods [32,33,41,42], and travelling with a partner or group for help in times of health need [29,33,43]. Solo travellers sought some degree of social engagement with the locals and fellow travellers, especially those from similar countries of origin [30,33–35,37,41,43].

Not all travellers were able to practice self-care without difficulty. Travellers reported psychological challenges such as anxiety, fear, and worry that occurred as a result of both personal and environmental deficits [30,31,33,38,39,42]. For example, travellers without legal status feared being detained and deported [30,31]. Meanwhile, elderly travellers lacking physical fitness were worried about demanding physical activity, although some benefitted from increased physical activity to maintain or improve their health and fitness [33]. Other travellers struggled to manage physical activity due to unpredictable schedules and competing priorities for self-caring for their chronic illness [33,42]. Addressing these psychological concerns with preventive self-care was needed to maintain mental well-being.

Facilitated self-care

Self-treatment in any form, such as self-medication and self-management, was often a response to layered barriers to accessing healthcare services [29–31,34,37,40,42,43,45]. Travellers used any products and services they could afford and access, even if they posed an additional risk and were not in line with the destination country’s regulations and policies [29–31,34,37]. Self-treatment with herbal and traditional medicines was not always perceived as superior to treatments from an authorised health professional, with some using it for a complementary purpose [30,40].

Adherence to prescription treatment may be compromised for those on treatment for acute or chronic conditions [30,33,40,45]. Some travellers intended not to adhere to the treatment they received due to side effects, for example [40,45]. Others became non-adherent due to uncontrollable factors, such as the mobile nature of travel and inaccessibility to products and services [30,33,40,45].

Depending on their perceived necessity and severity of an illness, travellers went to the nearest accessible health facility, with those offering free services preferred, such as community pharmacies, which provided free consultations [29,39,43,45]. Facilitation by a health professional improved travellers’ adherence to treatment [45]. Therefore, there was a need for facilitated self-care from health professionals and facilities that are accessible to travellers.

Limitations

There were five limitations in our study, including the migration status, researcher’s positionality, and research focus of the original studies, the COVID-19 context, and the risks of publication and selection bias. Firstly, establishing the travel or migration status of participants was challenging. However, this challenge was related to the body of literature, where some studies did not clearly define the participants’ migration status. Despite the small number of articles included in this review, the included studies reported data from a total of 769 participants, with two studies having more than 100 participants due to the multi-site settings and multiple stakeholders involved. Secondly, the majority of included studies (12 out of 17) did not report the researcher’s positionality, preventing us from conducting sensitivity analysis by excluding them to reassess the final themes. The qualitative design of the included studies also prevented us from conducting a weighting analysis. Thirdly, most of the synthesised studies focused on either an illness or a phenomenon, making this review potentially missing the full range of health problems faced by travellers and migrants. However, our search strategies did not limit the year of publication, ensuring a comprehensive retrieval of the current knowledge of the topic. Fourthly, none of the studies included in this meta-synthesis focused on the COVID-19 pandemic, which may impact the magnitude of self-care practices among travellers and migrants. However, this limitation also showed the scarcity of studies on travellers and migrants during the COVID-19 pandemic. Fifthly, excluding grey literature may introduce publication bias, as unpublished qualitative studies could provide additional perspectives. Also, including only qualitative components in mixed-method studies may introduce selection bias. To address potential publication and selection bias, we conducted a sensitivity check by excluding three borderline studies with two ‘No’ responses in the quality assessment. The five analytical themes remained unchanged, with only one descriptive theme (i.e., ‘Health Risk Management’) disappearing, suggesting that the synthesis was sufficiently robust to this exclusion.