Timothy pollen. Longer follow-up, but still no proven advantage

For patients with persistent hay fever despite allergen avoidance and symptomatic treatment, data available in 2007 did not favour sublingual desensitisation over subcutaneous desensitisation.There are still no comparative trials of sublingual versus subcutaneous desensitisation. A systematic review in a total of 410 children and adolescents, published in 2008, confirmed the lack of efficacy of sublingual lyophilisates of timothy grass pollen extract. A placebo-controlled double-blind trial was subsequently published, including 253 children aged 5 to 16 years, who were monitored during one pollen season. Preventive treatment with timothy grass pollen extract for about 5 to 9 months was associated with an average of 9 extra days without the need for symptomatic treatment during the pollen season, compared to placebo therapy. In children, the main adverse effect was itchy mouth (32% versus 2% with placebo). One child had to stop treatment due to an adverse effect that worsened from day to day. In adults who continue to suffer from hay fever despite symptomatic treatment, a summary of follow-up data from the randomised placebo-controlled trial of timothy grass pollen extract included in the initial assessment report has been published. However, it is too vague to assess the benefit in terms of the number of days without symptomatic treatment during pollen season (it was only 4 additional days after the first year of treatment). Most adverse effects observed in adults were local reactions. Data on possible severe adverse effects are scarce. In practice, the preventive effects of sublingual timothy grass pollen extract are very modest in both adults and children.There are no trials comparing this treatment with subcutaneous desensitisation. Adverse effects are frequent and mainly local reactions.