Sublingual immunotherapy (SLIT) is now recognized as a viable alternative to the classical injection route and it is currently used in everyday clinical practice in Europe. Sublingual administration is particularly attractive for children since it is completely pain-free. To date, no fatalities from SLIT have been reported, but two cases of anaphylaxis to inhalant allergens have been reported. The large majority of the adverse events reported in literature is described as mild. Most of them involve the mouth (burning or itching) or the gastrointestinal tract (stomachache, nausea) and usually self-resolve in a few days without any intervention. At present, SLIT represents the main option for allergists, however, tablet immunotherapy could become an interesting alternative to sublingual drops.