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1. Introduction
Cough is a highly prevalent condition and a common reason for consultations in general practice [1–4]. Most frequently, cough symptoms are caused by acute viral upper respiratory tract infections (URTIs) and the course is mostly benign and self-limiting, although bacterial superinfection may occur in acute bronchitis [5, 6]. For chronic cough, important causes are chronic obstructive pulmonary disease (COPD) and asthma which are characterized by airway obstruction and hypersecretion of mucus, additionally causing symptoms like wheezing or dyspnoea.
Inappropriate use of antibiotics for viral respiratory tract infections is a significant problem causing both pathogen resistance and substantial health care expenditure without affecting the resolution of cough [7]. Therefore nonantibiotic alternative treatment options are needed. Commonly used over-the-counter drugs for acute cough in both children and adults are mucolytic agents and antitussives, which are also widely prescribed in primary care settings [8]. In the UK, cough liquids accounted for sales worth 102 million pounds in 2008 [9]. Among these nonantibiotic cough remedies, herbal preparations containing extracts from the leaves of ivy (Hedera helix L.) enjoy great popularity in many European countries [10–12]. In 2007, more than 80% of herbal expectorants prescribed in Germany comprised ivy extract and amounted to nearly 2 million prescriptions nationwide and a volume of sales exceeding 13 million Euros [10].
Ivy leaf contains saponins which are considered to have mucolytic, spasmolytic, bronchodilatory and antibacterial effects [13, 14]. Despite widespread use of ivy leaf extracts, the effectiveness for the treatment of acute cough is not well established. Methodically strong clinical studies seem scarce despite the epidemiological and economic importance. To our knowledge, there is no comprehensive systematic review of the available clinical evidence. A Cochrane Review assessing over-the-counter cough medications does not cover herbal drugs [8]. Other reviews focus on effectiveness of ivy leaf extracts in asthma or COPD [12, 15–17]. Therefore, we performed a systematic review of the effectiveness and tolerability of ivy preparations for the treatment of acute URTIs in children and adults.
2. Methods
2.1. Data Sources
Our search included 3 electronic bibliographic databases: MEDLINE, EMBASE and the Cochrane Library. We included studies published from the respective inception of the databases until 20. December 2009. There was no language restriction. Search terms were: ivy, hedera, respiratory tract diseases,...