Last week marked a major milestone for 8-year-old Amelia, who flew across the country to eat a handful of nuts that, just months ago, would have sent her into life-threatening anaphylactic shock. She knocks back small medicine cups containing a mix of cashews, peanuts, sesame seeds and hazelnuts, washes it down with water, and waits.

As the moments pass in the small Redwood City clinic, so does the anxiety. The intense food allergies that complicated Amelia's life for years -- forcing her to sit alone during lunch and bring her own food and cupcakes to parties -- were finally in the rearview mirror. Conversations with Amelia's mother quickly turned from frightening allergic reactions to the prospects of eating chocolate walnuts and peanut M&Ms.

Amelia is the latest patient to complete her treatment at a new allergy clinic on the Peninsula that uses oral immunotherapy to desensitize patients to food allergens, a rare method of treatment that has drawn families from all over the United States and beyond. The strategy involves ingesting the very same substances that cause a violent reaction, albeit in very small doses, to build up a resistance, and over time patients are able to ramp up how much they can consume each day without an adverse reaction.

Oral immunotherapy was considered radical just a few years ago, but a growing body of research from clinical trials shows it can be a safe and effective way of controlling crippling food allergies.

Dawn Orso, Amelia's mother, told the Voice that she was forced to be ever-vigilant with Amelia's peanut and tree nut allergies for nearly all of her daughter's life. Shots of epinephrine, better known as EpiPens, accompanied Amelia wherever she went, and Orso said she has had to use them in the past in order to stop her daughter's severe allergic reactions. The household became a nut-free zone out of necessity, the list of restaurants they could visit narrowed down to just three and anxiety hung over trips to public places like the pool or the park down the street.

"During this time she was sitting alone at lunch, and could maybe have one friend with her," Orso said. "We would bring our food with us everywhere we went."

When Amelia reached age 4, Orso resolved to get her child into one of the clinical trials conducted by prominent universities throughout the country to desensitize her to the dangerous foods, unsuccessfully entering her into one lottery after another. Not only was she vying against thousands of other parents with children struggling with food allergies, but criteria for joining a clinical trial often restricts who can apply at all.

Keeping trials on her radar eventually paid off: Starting last year, Whitney Block launched her own private clinic to start treating allergy patients. She was one of the nurse practitioners who participated in oral immunotherapy trials at El Camino Hospital in Mountain View conducted by Stanford University's Sean N. Parker Center for Allergy and Asthma Research.

Orso got her foot in the door right away and jumped on the opportunity to be one of the first patients, even though it meant making several flights to the Bay Area from her home in Maryland.

"We signaled we were interested as soon as she was ready to go," Orso said.

An overwhelming need

Block, a lead nurse practitioner at Stanford's allergy research center, has participated in the university's groundbreaking trials aimed at desensitizing children to food allergies since 2013. Though numerous doctors and researchers co-author the studies, Block was often the person parents and children saw when it came time to ingest a higher dosage.

The results of the trials have had huge ramifications for families dealing with food allergies. Last month the university wrapped up a study showing that children with multiple food allergies can accelerate the desensitizing process by coupling treatment with shots of the asthma medicine omalizumab, better known as Xolair, which brings down the body's allergic response.

During her work with Stanford, Block said she saw an overwhelming need from families seeking the treatment who were stopped at the door, either because of space constraints or because of ineligibility for the specific trial -- which could exclude children for a plethora of reasons, such as disallowing siblings. Patients in trials might also be put in the placebo group, which obviously doesn't see the same benefits of those receiving the treatment.

Despite the slim acceptance rate, she recalled getting tons of inquiries from people who were willing to make massive sacrifices in hopes of getting their child's allergies under control.

"I just realized how many people really need and could benefit from the therapy, and that's what made me want to offer the therapy outside of clinical research," Block said. "My first patients were from Maryland and Boston, so they're definitely traveling, and I feel horrible for people doing that cross-country trip every few weeks and every few months."

So Block took matters into her own hands, and in August opened up her own clinic offering the same service -- oral immunotherapy with and without Xolair injections -- to patients out of a small office across the street from Sequoia Hospital in Redwood City. The clinic is open one day each week and serves as a medical office for a urologist during its off-days, so it takes a bit of redecorating the walls with allergy-related charts and graphics before it starts to feel like home, Block said.

It didn't take long for the waiting list to build up, with families seeking treatment from as far away as Bulgaria, Block said.

Recent estimates found that close to 6 million children under the age of 18 suffer from food allergies in the United States, the majority of whom are allergic to peanuts, eggs, milk, tree nuts, wheat, soy, fish and shellfish, according to the nonprofit Food Allergy Research and Education (FARE). The prevalence of childhood food allergies has also sharply increased over the last two decades, increasing by 50 percent from 1997 to 2011, and the number of children hospitalized for allergic reactions to food each year has likewise tripled over roughly the same period.

Block recalled one boy who, before oral immunotherapy, would violently vomit just by coming in contact with milk, and another child who suffered a severe allergic reaction on an airplane after touching one of the small table trays that had a leftover peanut residue.

While the jury is still out on what's causing the sharp increase, one of the prevailing theories is the so-called hygiene hypothesis: The idea that creating a germ-free environment for children at a young age weakens the immune system, making the body more likely to rebel against common food allergens.

Despite several studies showing the effectiveness of oral immunotherapy, a clear need for the treatment and patients willing to travel far to get it, it's still extremely rare and difficult to find. Orso said she resigned from her job a year ago, in part to commit to the treatment and series of flights to the Bay Area in order to treat Amelia's multiple food allergies. At the clinic last week, she cracked open a log showing how she diligently tracked her child's dosage of peanuts and tree nuts every day since last summer, ensuring that Amelia was on track to graduate from the clinic this month.

"Unfortunately, no one on the East Coast is doing what Stanford is doing, and with all the research that we've done, there's no program that was as safe and as efficient," she said. "They aren't using Xolair, and they aren't doing it in an outpatient setting outside of a clinical trial."

Block said it takes a long time for the medical community to feel comfortable with a new treatment still being explored in clinical trials -- particularly the safety concerns that arise when purposefully feeding known allergens to children -- and that it may be a while before big companies and medical institutions jump on the opportunity. She said it took years of direct participation in the trials before she felt like she could provide a safe environment for her patients in a private clinical setting.

Allergists have started to warm up to the idea of doing oral immunotherapy, but they've been largely hesitant up until now, Block said. Very few people have been trained to do the treatment, which is far from mainstream at this point and is not taught in medical schools. Stumbling through the desensitizing process can have dangerous consequences.

"It's life or death if you get a dose wrong, if you get a dosing step wrong," Block said.

Easing the anxiety

Alameda resident Kate Rome said she was anxious about the treatment, which ran against years of vigilance to keep her 11-year-old child, Haley, away from peanuts. But with Haley quickly approaching middle school, protecting her from an allergic reaction was likely to get a whole lot more complicated, and she felt it was time to resolve the food allergy once and for all. When it came time for Haley to ingest peanuts at the clinic for the first time, Rome said she came to the appointment armed with an EpiPen, just in case.

"It's pretty crazy, what you're supposed to do," Rome said. "The first time (Block) dosed her I was very nervous."

Although Haley's treatment officially ended late last year, she and other patients who leave the clinic need to preserve the built-up immunity by continuing to ingest the allergy-provoking foods each day. The so-called maintenance dose is extremely important, Block said, and patients who stop taking the prescribed amount can start having reactions in just days. Patients are also advised to avoid exercising right after taking maintenance doses, which can lower the threshold for a reaction.

Though the bulk of patients are school-aged children, particularly kids about to enter elementary or middle school, Block said she sees patients as old as 33. She said it's possible adults are simply too busy with careers and other obligations and have lived with their allergy for so long that they don't bother with treatment. She said adults and teenagers heading to college are also the most likely to skip maintenance doses and lose their resistance.

Despite the ongoing maintenance, Rome said the difference has been like night and day. She no longer has to tread carefully with Haley everywhere they go to avoid allergic reactions, they can shop at grocery stores like Trader Joe's, and trips to restaurants, birthday parties and potlucks are no longer a trust exercise. Haley isn't a big fan of peanuts now that she can eat them -- a fairly common trait among kids with peanut allergies -- but she enjoys Kit Kat bars and candies that, until now, were off limits.

"When we drop her off at someone's house I don't have to look around anymore," she said. "It's the benefit of being able to relax just a little bit."

At each appointment, parents say that Block played a key role in making the treatment process a lot less scary, offering a level of calm and confidence for both parents and children. Each child coming in for an appointment is greeted with a warm welcome and a level of chatty familiarity that eases the tension in the room.

Rome said she doesn't plan to discard her EpiPens anytime soon, and still feels like she's on guard to protect Haley from her peanut allergy. But she predicts that the anxiety will slowly wane, and that she will eventually acclimatize to the new normal of not having to fret constantly about her child's safety.

"You don't know how to be a little less vigilant at first, but you try," she said.

A growing field

Recent clinical trials have chipped away at the conventional wisdom that the best way to deal with a food allergy is avoidance. Along with oral immunotherapy, studies have explored the usefulness of treating patients with small amounts of allergens through drops under the tongue as well as via small patches worn on the skin. Some companies are rapidly seeking approval by the U.S. Food and Drug Administration to get products like peanut allergy pills and patches approved and be the first to break into the market.

For now, Block said she's skeptical. Treatment through patches could potentially work, but it's still an unproven technique and is in the research trial phase to see how well it sizes up to oral immunotherapy. Results from sublingual immunotherapy -- the under-the-tongue treatment -- tends to build immunity much slower and doesn't bring people up to the same level of tolerance. What's more, many of the products being tested are intended for just peanut allergies, and don't do much to help children suffering from multiple allergens.

One of the more prominent companies, France-based DBV Technologies, announced plans to submit an application to the FDA for a new peanut patch product this year. But the company fell short of meeting important benchmarks during late-stage trials on October, which tested the product on hundreds of children ages 4 to 11 years old, causing its stock to plummet by more than 60 percent.

Other companies are taking a different route, seeking to put food products on the market that can build up a tolerance at an early age in order to prevent a full-blown allergy from developing in the first place. A landmark 2015 study found that introducing peanuts into an infant's diet can dramatically reduce the chances of developing a peanut allergy by age 5, and the FDA has since released new guidelines allowing foods to claim they can prevent a food allergy.

"The new advice about the early introduction to peanuts and reduced risk of developing peanut allergy will soon be found on the labels of some foods containing ground peanuts that are suitable for infant consumption," according to FDA Commissioner Scott Gottlieb in a September statement. "Our goal is to make sure parents are abreast of the latest science and can make informed decisions about how they choose to approach these challenging issues."

The Menlo Park-based company Before Brands is jumping on the opportunity, securing millions in investor funding to launch products aimed at reducing the risk of developing an allergy to peanuts, milk, tree nuts, eggs, fish and other common allergens.

For Block, she has her own ambitions. She said she plans to extend her clinic to two days per week soon, and is seriously considering opening up a clinic in New York, Boston or the Washington, D.C. area to extend her service to families who would otherwise face a long trek to the Bay Area. She said young patients like Amelia have had to give up so much, missing out on school to take flights for appointments.

One of those trips unfortunately coincided with Halloween. To make up for it, Orso said Block showed up at the hotel the family was staying at and, dressed up as Snow White, picked Amelia up and took her out trick-or-treating. As an added benefit, Block said, Amelia got to eat some of the treats she would normally have to discard, thanks to the progress she had made building up a tolerance to nuts.

Orso said she thrilled with the treatment, and that she always felt like Block was looking out for her child the whole time.

"She monitored Amelia throughout the whole process -- it really eased the concerns I had," she said. "So much so that I fly across the country just for Amelia to eat half a nut."

More information about the new clinic is online at wmboit.com.