Small amounts of allergens administered sublingually is a safe, effective alternative to allergy injections or to the use of other medications for some people, according to a report published in JAMA.

Investigators reviewed 63 published studies, almost all of which were conducted in Europe, involving sublingual immunotherapy. While not approved for use in the US, allergy drops have been widely available in Europe for nearly two decades.

In eight of 13 studies evaluated, researchers found “strong evidence” that drop therapy produced a 40% or greater reduction in coughing, wheezing, and tightness in the chest compared with other treatments, including inhaled steroids, according to the authors. Nine of the 36 studies showed that allergy drops produced a 40% or greater reduction in symptoms of runny nose, sneezing and nasal congestion, results the authors described as “moderate evidence” in support of using sublingual immunotherapy.

“Our findings are clear evidence that sublingual immunotherapy in the form of allergy drops are an effective potential treatment option for millions of Americans suffering from allergic asthma and allergic rhinoconjunctivitis,” says senior study investigator Sandra Lin, MD, who cautioned that drop therapies may not be for all sufferers of allergic rhinoconjunctivitis and allergic asthma. Lin advised patients to weigh the risks and benefits of sublingual immunotherapy before deciding on long-term treatment options.