Regina Barber (2:43)

That's Dr. Gina DePoul Hidalgo. I, I invited her to the NPR studios because she's a pediatric and adult allergist in the D.C. suburbs. And she very patiently began our conversation with a recap of what allergies are.

Dr. Gina DePoul Hidalgo (2:56)

You usually had to have been exposed to the allergen in the past. And it's that first exposure where your body ends up making allergic antibodies, what we call IgE, or immunoglobulin E, antibodies to those allergens.

Regina Barber (3:10)

People's bodies have been doing this, encountering allergens, overreacting, creating these allergic antibodies for a long time, which means doctors have been trying to treat it for a long time.

Dr. Gina DePoul Hidalgo (3:23)

Most patients, we end up recommending things like antihistamines, nasal sprays, eye drops, really more symptomatic treatments to help decrease your symptoms so you can, you know, be around the allergen and be somewhat okay.

Regina Barber (3:36)

Claritin, Zyrtec, Allegra.

Dr. Gina DePoul Hidalgo (3:39)

They're really temporary kinds of treatment options.

Regina Barber (3:42)

But what if I told you there was another kind of treatment that worked for all but the most severe allergies, one that didn't just treat the the symptoms of your allergies, but the actual cause of them?

Dr. Gina DePoul Hidalgo (3:52)

The idea is that you build tolerance over time by giving you what you're allergic to, you get desensitized to those allergens that you're being treated with. Unlike medicines, which only take care of the symptoms, allergy shots are actually training your immune system to react differently when you're exposed to the allergens.

Regina Barber (4:11)

So today on the show Allergy Treatments, we're learning where our allergies come from, how they're detected, and even how to treat them so they're effectively gone. You're listening to shortwave from NPR.

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So, Dr. Gina.

Regina Barber (5:39)

Can I call you Dr. Gina?

Dr. Gina DePoul Hidalgo (5:40)

Yes, you can call me Dr. Gina.

Regina Barber (5:41)

Excellent. Let's start with allergies. I was well into my adulthood when I finally, like, did the allergy panel to check if I had allergies. Cause I suspected. Can you, for our listeners, tell us how does this test work? Yes.

Dr. Gina DePoul Hidalgo (5:56)

So how it works is that we're actually introducing these allergens into your skin. There's different forms of testing, but the main common one is what's called a skin prick.

Regina Barber (6:05)

Yeah. It looks like a meat tenderizer. Just boom. On your skin.

Dr. Gina DePoul Hidalgo (6:08)

Right on the skin, yes. So the idea is that by exposing your skin to that, if your body has made those allergic IGE antibodies, it recognizes it, it binds to it, and then within 15, 20 minutes, you get a little red itchy spot at the site of where those allergens are.

Regina Barber (6:26)

Yeah, I found out I was allergic to. Let me read this, starting from most intense to least intense. Basically all grasses, dust mites, some tree pollen and weeds. Cats. I have four cats. Cockroaches, equal to cats, feathers, mosquitoes.

Regina Barber (6:43)

What's happening in my body when I encounter these allergens?

Dr. Gina DePoul Hidalgo (6:47)

So what happens when you encounter the allergen is that your body is exposed to that allergen. Let's just use cat, for example. And then the IGE is waiting for its partner, and then it binds to that allergen. That ige again, is an immunoglobulin E, which is the allergic antibody. And then within 15, 20 minutes, it releases chemicals like histamine, prostaglandins, leukotrienes. It's these chemicals that actually cause the symptoms that are related to allergy within 15, 20 minutes.

Regina Barber (7:17)

The itchy, the water. Yes.

Dr. Gina DePoul Hidalgo (7:19)

Itching, congestion, sneezing, all of that.

Regina Barber (7:22)

So why am I not bothered by my four cats? Like, I've had four cats for the last year and a half and I'm just not that bothered by it. But it's like in the middle of my, my allergy spectrum of like.

Dr. Gina DePoul Hidalgo (7:34)

Of reactivity.

Regina Barber (7:35)

Of reactivity. Yeah.

Dr. Gina DePoul Hidalgo (7:36)

Got it. So the fact that you don't have symptoms means that you might not have a clinical allergy or clinical significance to the allergy test, but you're primed for. So there may be certain breeds of cats, for example, that you might have issues with. Yes. And maybe not necessarily your cats. So it's the idea of you've made these allergic antibodies that are waiting on your mast cells, and then when you are exposed to it, there are certain ones that may say, oop, I'm going to be releasing my histamine from these mast cells and cause the symptoms. So the way to see it is that you are sensitized, meaning you were exposed to it. Your body made those allergic antibodies. But now not everybody actually has a clinical reaction, but a majority of people do.

Regina Barber (8:22)

Oh, wow. I was also fascinated. I asked the doctor this, the allergist. I do feel like, a little bit bothered by them, but not a lot. And he's like, well, you'll notice if you go on a long trip and come back.

Dr. Gina DePoul Hidalgo (8:32)

And come back. Exactly.

Regina Barber (8:33)

So why is that?

Dr. Gina DePoul Hidalgo (8:34)

So we have people, you know, who really experience that. For example, you lived with a cat, and then you go off to school, and then you come back home and all of a sudden, like, to college. Yes, to college. And then you come back home for break or the summers, and you're like, oh, my goodness, why am I having this? And, you know, the opposite of allergy is tolerance.

Regina Barber (8:53)

Yeah. Okay.

Dr. Gina DePoul Hidalgo (8:54)

So when you're exposed to something quite frequently, then you're not going to be allergic to it because your allergic antibodies are not going to be, you know, releasing these chemicals all the time. So if you are around something, then it's likely that you're more tolerant to it than allergic.

Regina Barber (9:09)

And. But those. That panel still picked up that I am allergic to cats.

Dr. Gina DePoul Hidalgo (9:13)

I wouldn't say allergy necessarily, but that you're sensitized to it.

Regina Barber (9:18)

So this is where this idea of, like, allergy immunotherapy, basically exposure therapy through allergy shots comes in. After I did that allergy panel we were talking about, the allergist came back and he was like, oh. And he was like, wow, you would be a great candidate for allergy shots. And I had never heard of these shots before. So can you tell me a little bit about the history, like, who first came up with these allergy shots and when?

Dr. Gina DePoul Hidalgo (9:43)

So it was actually introduced over 100 years ago. So in 1911, a brave British physician named Dr. Leonard Noon started purifying the grass extracts because he hypothesized that there's some toxin. They used the word toxin back then, that there was some kind of toxin that was causing these symptoms and that by inoculating these patients with increasing doses of grass pollen, that it would decrease the symptoms and desensitize them. And so those were the first reports in the early 1900s that allowed us to see what we now call allergen immunotherapy and allergy shots. That's the history behind when it started.

Regina Barber (10:24)

Yeah, and it's since developed. So how has it changed then? As you know, time has gone on.

Dr. Gina DePoul Hidalgo (10:31)

So now it's more refined. There are actually companies that make the allergen. You know, they grow the pollens, they grow the plants, and it's purified and extracted so that it's much more refined than when it was many, many years ago.

Regina Barber (10:45)

Got it. Okay, so can you tell our listeners like how that process works? Like it's not just one shot, it's a series of shots?

Dr. Gina DePoul Hidalgo (10:51)

Yes. So there's different protocols, but exactly what you're going through is the typical, you know, standard schedule. So the idea is that you're starting off with very dilute doses and then you come once a week for several months. And then at some point when you reach this target dose or maintenance dose, then you can come every two to four weeks, depending on the protocol. So it's two phases, what we call the buildup phase, which is all that going once a week, coming, coming, and then, then there's the maintenance phase, which is then the once every four weeks. And the idea is once you get to that maintenance dose, the amount that's in that maintenance dose has been calculated. So it contains the amount that has been shown to be effective.

Regina Barber (11:35)

But does it always work? Like, am I cured? Like do I have to do shot every month for the rest of my life or no.

Dr. Gina DePoul Hidalgo (11:42)

So this is something we get asked all the time. So the idea is that by getting to the maintenance dose, you actually we recommend about a three to five year.

Regina Barber (11:51)

Therapy of just going once a month. Yes.

Dr. Gina DePoul Hidalgo (11:54)

And there is no cure for allergies per se, which is why we can't say this is going to cure you.

Regina Barber (11:59)

But I was telling everyone that I'm like, these shots are going to cure me.

Dr. Gina DePoul Hidalgo (12:02)

And they're like, no, the closest thing to a cure. But in general it's long lasting effect. And I have had some patients who did this years ago because. Right. This has been out for a over 100 years. Some that did this in their like middle elementary school. They'll come back to me in their 60s and say, oh, Dr. Gina, I want to start shots again because I feel like my Symptoms have come back. So in that case, that was decades of being asymptomatic to their allergen. So again, it's very individualized, which is why we can't say, oh, you know, this will cure you. But really, the percentage that we really tell patients, it's anywhere from 80 to 90% effective for those who start shots.

Regina Barber (12:40)

Okay. So, you know, I'm not asking for myself, just for a friend, like, is there any side effects from these allergy shots that I've been taking?

Dr. Gina DePoul Hidalgo (12:49)

So there is the potential for something to happen in the sense that you can get a little swelling at the site of where the injection is.

Sponsor/Advertisement Voice (12:58)

Right.

Dr. Gina DePoul Hidalgo (12:58)

Because technically those are the allergens being introduced. But another potential reaction can be what we call a systemic or anaphylactic reaction, where it's whole body reaction, you know, from hives, trouble breathing, nausea, vomiting, swelling, which is very, very rare if it's again administered safely. But all of these side effects are typically mitigated because you are usually observed for a certain period of time.

Sponsor/Advertisement Voice (13:21)

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Regina Barber (13:22)

Yeah. They're like, gina, you should stay here for a little while. And I had to do that four times in a row.

Dr. Gina DePoul Hidalgo (13:26)

Exactly. So there's an observation period to make sure that these reactions don't happen. And of course, wherever you are getting the allergy shots, there's usually trained staff. So if something were to happen, again, very, very rarely, we're able to administer the proper treatment to reverse it. Right.

Regina Barber (13:43)

So, you know, we've been talking a lot about cats. What about food allergies? Thankfully, I'm not allergic to any food. But are food allergens any different from the allergens we've been talking about?

Dr. Gina DePoul Hidalgo (13:53)

So, yes, actually, the mechanism is the same, but the treatment is potentially different depending on what the allergen is. So there's no allergy shots for foods that is not yet available, but there is therapy that's called oral immunotherapy, where it's giving you increasing doses of the food, similar to how we talked about with allergy shots. But it's the food that you are actually getting increasing doses of orally. So some allergists practice this.

Regina Barber (14:25)

This is, like, so interesting, right? Because I remember when I was pregnant with my daughter, this was more than 15 years ago, the advice that was being given to us was do not expose your kids to certain foods like peanuts and eggs and even strawberries before, like, I think, 1 years old or something like that. And I've noticed that the guidance has basically reversed since then in favor of the like early introduction. Why did that change?

Dr. Gina DePoul Hidalgo (14:51)

Yes, so it's exactly what you're saying, which is we didn't have it. Right, Right. So it was like 2008. Ish.

Regina Barber (14:58)

2008. She was born in 2008.

Dr. Gina DePoul Hidalgo (15:00)

Yes. And the guidance back then was avoid the allergenic foods until age 3. And we're like, okay, we're gonna avoid these allergenic.

Regina Barber (15:07)

And then my Chinese mother just gave her everything and she was like, not even one. And I was like, well, I guess she's fine.

Dr. Gina DePoul Hidalgo (15:13)

Yes. And so after those recommendations back then we saw this huge prevalence of peanut allergy and we're like, what is going on here? And then there was a game changing study in 2015 that was actually about a peanut allergy and high risk patients and babies. And they found that by introducing peanut between four to six months of age, but definitely before one of age, it actually decreased the incidence of peanut allergy in these high risk kids. So after then. So now for a decade we've been telling parents and you know, advising our pediatrician colleagues, early introduction of allergenic foods. Early introduction of allergenic foods.

Regina Barber (15:52)

So my mom was right. Please don't tell her.

Regina Barber (15:56)

Dr. Gina, thank you so much for talking to us today.

Dr. Gina DePoul Hidalgo (15:59)

Thank you so much for having me, Regina.

Regina Barber (16:03)

If you like this show, we have done so many episodes on allergies. We'll link those episodes in the show notes. This episode was produced by Hannah Chin. It was edited by our showrunner, Rebecca Ramirez, and the facts were checked by Tyler Jones. Kwesi Lee was the audio engineer. Beth Donovan is our vice president of podcasting. I'm Regina Barber. Thank you for listening to Shorewave from npr.

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