Sublingual immunotherapy, which involves placing allergen drops under the tongue, can reduce hay fever symptoms on 62% fewer days during allergy season compared to placebo, according to clinical trials. This approach represents a significant shift in how allergists treat the 400 million people worldwide who suffer from allergic rhinitis, the medical term for hay fever and related nasal inflammation caused by airborne allergens like pollen and dust mites. For decades, most people with hay fever have relied on antihistamines or nasal sprays to manage sneezing, itchy eyes, and congestion. But a growing body of evidence suggests that a different class of treatment, allergen immunotherapy (AIT), offers something these symptom-relievers cannot: the ability to retrain the immune system to stop overreacting to harmless substances. Unlike medications that mask symptoms, immunotherapy can potentially prevent hay fever from progressing to asthma, a serious complication that affects millions of allergy sufferers. What Is Sublingual Immunotherapy and How Does It Work? Sublingual immunotherapy involves placing drops containing small amounts of an allergen, such as birch pollen or grass pollen, under the tongue several times per week. The body gradually becomes desensitized to the allergen, reducing the immune system's overreaction. This approach emerged as a safer alternative to allergy shots, which require regular office visits and carry a small but documented risk of anaphylaxis, a severe allergic reaction. The history of this treatment spans more than a century. In 1911, a doctor discovered that injecting pollen extract could alleviate hay fever symptoms the following spring. By the 1950s, the first double-blind, placebo-controlled trials of grass pollen immunotherapy were conducted, and by the 1980s, injection immunotherapy had become a recognized treatment. However, between 1957 and 1986, approximately 26 deaths in the United Kingdom were linked to anaphylaxis from subcutaneous immunotherapy, prompting stricter safety protocols that required patients to wait in doctors' offices for observation. "He showed up at my house with a case of wine because I had completely changed his life in the spring," said Glenys Scadding, describing one of her first sublingual immunotherapy patients forty years ago whose hay fever was so severe he couldn't walk to the local train station without getting out of breath. Glenys Scadding, Vice President of Euphoria and Honorary Consultant Allergist and Rhinologist at University College Hospital in London Sublingual therapy, pioneered by Scadding in the 1980s, initially faced skepticism. "Sublingual administration was considered a 'margin' that wouldn't work," Scadding noted. However, research has since demonstrated that sublingual drops carry a much lower risk of anaphylaxis than injection therapy while remaining highly effective. There have been no deaths associated with sublingual immunotherapy, and serious adverse events are very rare, though local reactions such as temporary itching or swelling of the tongue are more common. How Effective Is Sublingual Immunotherapy for Hay Fever? Clinical evidence supporting sublingual immunotherapy is compelling. In one trial led by Stephen Durham, a clinical allergist and professor of allergy and respiratory medicine at Imperial College London, participants with pollen allergies who received a placebo reported severe hay fever symptoms on 16% of days during allergy season. Those who received sublingual drops reported severe symptoms on only 6% of days, a reduction of 62%. The treatment requires commitment. Patients must take the tablet under the tongue every day for eight to sixteen weeks before the start of pollen season. If therapy begins sixteen weeks before pollen season, patients experience symptom control during the season in approximately 85% of cases. The World Health Organization issued a statement in 1998 recognizing sublingual administration as a promising alternative to injection therapy, giving it legitimacy on a global scale. "If you treat people for three years, you can induce long-term remission of the disease," explained Stephen Durham, noting that continuing treatment throughout the year for three years offers the best outcomes. Stephen Durham, Clinical Allergist and Professor of Allergy and Respiratory Medicine at Imperial College London Long-term treatment appears to offer lasting benefits. Patients who continue sublingual immunotherapy for three years may experience remission of hay fever symptoms that persists even after treatment ends, though ongoing use is typically recommended. Why Is Hay Fever Being Overlooked as a Serious Health Condition? Despite affecting approximately one in four adults and one in eight children in the United Kingdom, hay fever is often trivialized by those who don't experience it. In the UK alone, allergic rhinitis leads to at least 16 million doctor visits annually, with similarly high figures in Australia and the United States. Yet many healthcare providers, including general practitioners, treat it as a minor inconvenience rather than a condition warranting specialized care. "Hay fever is a big problem and is often trivialized by those who don't have it. We work, sleep and have fun in our lives, and all of these things are seriously affected by hay fever," stated Stephen Durham. Stephen Durham, Clinical Allergist and Professor of Allergy and Respiratory Medicine at Imperial College London The impact of hay fever extends far beyond sneezing and itchy eyes. People with hay fever are more likely to experience difficulty falling and staying asleep, feel tired, and wake frequently at night. Seasonal allergies have been found to affect children's academic performance. Due to chronic inflammation of the mucous membranes, people with allergies experience more respiratory infections, with one study showing they have twice as many infections as those without allergies. When left untreated, hay fever can lead to severe, chronic upper respiratory illnesses and ear infections. Perhaps most concerning, hay fever in children can lead to the development of asthma, and asthma tends to be more severe in people who have hay fever. This connection reflects what allergists call the "one airway, one disease" concept, where inflammation in the upper respiratory tract can affect the lower respiratory tract. Steps to Access Sublingual Immunotherapy Treatment - Consult an Allergist: Rather than accepting a general practitioner's recommendation to simply purchase over-the-counter antihistamines, ask for a referral to an allergist or immunologist who can evaluate whether you're a candidate for sublingual immunotherapy. - Get Tested for Specific Allergens: Identify which allergens trigger your symptoms through allergy testing, as sublingual immunotherapy is tailored to specific allergens like birch pollen, grass pollen, or dust mites. - Plan Treatment Timing: Begin sublingual immunotherapy at least eight to sixteen weeks before your allergy season starts to achieve optimal symptom control during peak pollen months. - Commit to Long-Term Treatment: For the best results, including potential long-term remission, plan to continue sublingual immunotherapy for three years while taking the drops daily under your tongue. - Monitor for Local Reactions: Be aware that temporary itching or swelling of the tongue may occur, but serious adverse events are extremely rare, making this a safer alternative to allergy injections. Why Are So Few People Receiving Immunotherapy Despite Its Effectiveness? A major barrier to sublingual immunotherapy access is that very few people have the opportunity to visit an allergist in person, particularly during the early stages of disease when treatment is most straightforward and effective. Many general practitioners don't routinely refer patients to specialists or discuss preventative, long-term options like immunotherapy. Instead, they often direct patients to purchase antihistamines from a pharmacy, missing an opportunity to address the underlying immune dysfunction. This gap in care is particularly troubling given that hay fever prevalence is increasing. Studies show a rise in allergic rhinitis across Europe, the United States, and Australia, with growing evidence suggesting that hay fever symptoms are becoming more severe due to climate change. As pollen seasons lengthen and intensify, the need for effective, disease-modifying treatments like sublingual immunotherapy becomes increasingly urgent. For people struggling with persistent hay fever symptoms despite using over-the-counter medications, sublingual immunotherapy offers a scientifically proven alternative that addresses the root cause rather than merely masking symptoms. By retraining the immune system over time, this treatment can reduce suffering, improve quality of life, and potentially prevent the progression to asthma. The key is ensuring that allergists, not just general practitioners, are involved in treatment decisions from the start.
