Solve cat allergies with money

Jan 13, 2025

I would like to get a cat. One thing that has been stopping me is concern about allergies—not mine, but those of friends who I would like to host. After some research, the picture seems to be: for not less than $1000 over the lifespan of the cat, it's possible to have a cat that triggers substantially fewer and weaker allergic responses.

There are three (non-exclusive) options:

Option 1: Get a hypoallergenic cat
Option 2: Feed your cat anti-cat-allergen antibodies
Option 3: Spray your home with an anti-cat-allergen spray

People who are trying to solve their own allergies might also benefit from cleaning, medication, immunotherapy, or finding other ways to reduce inflammation.

Option 1: Get a hypoallergenic cat

Some cats provoke no allergic response or weaker allergic responses, and this is consistently true for some breeds of cats. The relationship between allergen levels and allergenicity is unstraightfoward1, so in order to determine the hypoallergenic potential of some breeds of cats, I identified Reddit comments with personal anecdotes about having (or not having) allergic reactions to cats of different breeds and coded them as one of:

⁠No reaction
⁠No reaction after adjustment period
Reduced reaction
Full reaction

Breeds commonly mentioned as hypoallergenic include the Siberian, Balinese, Russian Blue, Oriental Shorthair, Sphynx, Cornish Rex, and Devon Rex cats. I'm uninterested in hairless cats and aliens, so I only investigated the first three. Extending this to other breeds is left as an exercise for the reader.

There is much discussion on Reddit about the hypoallergenic potential of Siberian and Russian Blue cats; for those, I stopped when I realized that I had collected at least 50 comments. I only found 8 comments claiming personal experience with Balinese cats. Links to all comments are provided in a footnote.2

The data suggest that Siberians and Russian Blues trigger no reaction or reduced reactions for 70-80% of cat allergen sufferers. The sample size for Balinese cats is too small for me to feel comfortable drawing conclusions. There are some additional methodological nuances and concerns about interpretation, which I relegate to a footnote.3

This option costs around $2000, upfront.

Option 2: Feed your cat anti-cat-allergen antibodies

If you already have a cat, or are committed to getting a cat other than a Siberian or a Russian Blue, you have the option of feeding that cat Fel d 1 antibodies. These were introduced in a 2019 paper from Purina touting a 47% reduction in Fel d 1 levels after feeding cats food with added Fel d 1 antibodies. To be clear, the cats distribute less allergen because much of it is neutralized by antibodies added to their food. These take a few weeks to a few months to take effect.

Since then, a number of copycat (heh) products have come onto the market, though the method of production differs somewhat between them.

Purina LiveClear is made by inoculating hens with Fel d 1, then isolating and concentrating anti-Fel d 1 antibodies present in those hens' eggs, and then adding those antibodies to Purina dry food.
Catigy, SaFeline Pet, and Bella Baking Accents expose hens to cat allergens by raising them alongside cats and/or adding shed cat fur to their nesting, then dehydrate and powder those hens’ eggs. The powdered eggs are sold to consumers to add to separately-purchased cat food.
Pacagen isolates camelid anti-cat-allergen antibodies and engineers yeast to produce the associated single-domain antibodies. These nanobodies are added to a supplemental food topper, which consumers add to separately-purchased cat food.

I repeated the methodology from Option 1 (simplified to Reduced Reaction / No Change) to determine how much success people had with this intervention. Links to the original comments are provided in a footnote.4

The sample sizes are obviously quite low here, likely because of how new these products are. I believe Purina LiveClear was introduced to the market in 2020, and the other brands are years younger.

I’ve put considerations about methodology and interpretation in a footnote5, but it’s worth noting here in the main text that a few people’s cats had strongly adverse reactions to Purina LiveClear (example 1 example 2). The same might happen with the supplementary antibody options.

The cost of this option depends on the brand used:

Purina LiveClear costs about $4.50/lb, while normal dry food costs about $1/lb. Assuming a cat eats a half pound of dry food per week and lives for 15 years, that’s a cost of $1365 over replacement over the lifetime of the cat.
Catigy/SaFeline/Bella Baking cost $15-25 for a month’s supply. That comes to $2700-4500 over the lifetime of the cat.
Pacagen costs $50 for a month’s supply. Under the same assumptions, that’s a cost of $9000 over the lifetime of the cat.

Many Redditors complain about the cost of these products. For what it’s worth, this product category is very new and prices will probably decline in the coming decade.

Option 3: Spray your home with an anti-cat-allergen spray

If you already have a cat, it has coated your home with allergens, and you need to neutralize those allergens with some urgency, the best option is to use an allergen-neutralizing spray. (It may also help to clean thoroughly, use an air purifier, etc.)

Different allergen sprays work through different means. To my understanding, the options are:

Allergy Defender (sometimes also called Allergy Asthma Clear) works by changing the pH of surfaces to break down allergens.
Allerpet works by creating a protective barrier on surfaces to trap allergens. Note that, unlike the other sprays, Allerpet is applied directly to the pet.
Pacagen contains anti-cat allergen antibodies, which bind to cat allergens and prevent them from triggering an immune reaction.
Allersearch and Live Pure have proprietary formulas, which probably work by some combination of breaking down allergens and creating barriers to trap them.

In case it’s helpful, here are the ingredients of these different sprays:

As before, I scoured Reddit for comments relating experiences with these sprays. Links to the original comments are provided in a footnote.6

Methodological/interpretation considerations are similar to those for the section on foods with anti-cat-allergen antibodies. I’ll just note that the degree of allergy reduction depends on the spray used—e.g. all of the Allerpet anecodotes except for one mentioned using it alongside other interventions, like air filtration or frequent laundering, where Pacagen was more likely to be sufficient on its own.

The cost of using the spray will depend on the size of the space that needs to be treated, so I will just report the cost of 32 oz of each at time of writing:

Allergy Defender: $15
Allerpet: $61
Pacagen: $172
Allersearch: $14
Live Pure: $20

Again, because Allerpet is applied directly to the pet, this comparison overstates the cost of using it, but users will still need to use another method to clean the environment. Pacagen is just expensive, lol.

General impressions

Reading back over what I’ve written, I notice that I’ve gotten some general impressions that don’t come through very clearly in the data I’ve presented. Specifically, in terms of proportion of people who are helped and the extent to which their allergies are reduced, the most effective interventions seem to be:

Pacagen spray
Purina LiveClear, and probably the Pacagen cat food topper
Getting a Siberian or Russian Blue (or maybe one of the aliens)
Other foods, and other anti-allergen sprays

For my purposes, hosting moderately-allergic guests ~1 x/mo in a small apartment, using the Pacagen spray to prepare for their visits seems like a good solution. People who are allergic to cats and expect to be guests where cats are kept could benefit from taking a bottle of the Pacagen spray with them.

For people who are allergic to their own cats, especially those who live in a full-sized houses, spraying Pacagen across the entire living space every 2-3 days seems effort-intensive and expensive, so it might be better to get a hypoallergenic cat and/or feed the cat anti-cat-allergen antibodies. Using the Pacagen spray during any adjustment period could still be helpful, of course.

It’s a bit disappointing that no intervention was perfectly effective, but my review of the evidence leaves me believing that, in almost all cases, cat allergies can be entirely eliminated or substantially reduced, which is great news.

It's common for people to cite the 47% average Fel d 1 level reduction found in Purina's study introducing the LiveClear formulation, but this doesn't correspond to a 47% reduction in symptoms. Obviously there's no a priori reason that allergen response should be exactly proportional to allergen amount. Moreover, there are at least 8 cat allergens, LiveClear only acts on Fel d 1 levels, and different people respond to different allergens to different degrees, so the efficacy of LiveClear in reducing allergic responses will depend on the person as well as the cat.

To make matters more complicated, the allergenicity of Fel d 1 (and presumably other cat allergens) also depends on the specific form that the allergen takes. Fel d 1 is a heterodimer made of two ~17 kDa subunits, and pairs of ~35 kDa Fel d 1 proteins (“single heterodimers”) can join to form a ~70 kDa protein (“double heterodimer”). Smaller Fel d 1 conformations, especially <17 kDa core fragments, tend to be less allergenic than larger conformations, and so two cats with the same overall amount of Fel d 1 protein can be differently allergenic if their Fel d 1 manifests in different forms.

The most concrete data I was able to find on this comes from a masters thesis investigating the allergenicity of Siberian cats compared to domestic shorthair (DSH) controls. Though there were no differences in Fel d 1 concentrations in saliva and fur, the Siberian cats were reported to be much less allergenic than controls. The author attributes this to an abundance of ~35 kDa single heterodimer Fel d 1 in Siberians vs an abundance of ~70 kDa double heterodimer Fel d 1 in the DSH controls. (Note that the data in this paper likely understates the extent to which Siberians have lower overall levels of Fel d 1 than standard DSH, as controls were much more likely to be neutered/spayed and were on average older, both of which are associated with lower Fel d 1 levels.)

It may well be that allergen concentration is related to allergen conformation, with concentrations of double heterodimer Fel d 1 increasing superlinearly with increases in overall Fel d 1 levels. A plausible model that would permit this behavior would be one where the kinetics of heterodimer conformation are governed by second order dynamics in the forward reaction (single to double) but first order dynamics in the backwards reaction (double to single). Santorini suggests that something like this might be the case in her masters thesis, but to my knowledge this hasn't been directly investigated.

Siberian

No reaction: Morieta7 dontcryferguson kowe13571 pnda0828 TheHouseGuest billybobsparlour CaptainFlynnsGriffin Surfinsafari9 Itzbamwestin Living_Direction704 aliasson quartzresonance boonepii Odd_Ebb_1224 foxyyoxy TheLifeAquatic EBlackR Xukzi raskovixen OkTheseAreMyThoughts
Adjustment period: ElevenKangaroos deleted Tehshayne Minarch atramentum Busy_Acanthaceae1751 pure_Alps1050 mochigojo Dragonfly_Local SummertideSorrow
Reduced reaction: BoxxcarCadavers crack_n_tea haakonash awwwws dougmd1974 hk1026 urbanpandauk Im_The_One bostiebeastie owlgal1985 Legitimate_Pen9937 lucyisnotcool orangewurst alanonymous_ Anek70 JollyRazz littlenuggie29 Hufflepunk36 lehmlar
Full reaction: potatox2 Cabbage-floss sleepypeanutparty RochSpitz JuniorSkye6863 WhiskeyAndWhiskey97

Russian Blue

No reaction: quartzresonance crabman816 DerekComedy -whatdidyoudo- deleted believegatsby acceptablemadness ZweitenMal Lukn Greengirl_100 agia9891 Jenniyelf Grehdah valleyofdawn Additional_Hand5255 ExtraGravy- iwaoi_hell NckyDC RnRoger SpoopySpydoge Letthatpokeymanburn DeskadresJP remmij CynthBot
Adjustment period: remyluna19 MeaningOfLife-7 mpdjpl DuckPresident1 BeastieNoise maxt3r
Reduced reaction: b2armst physlizze deleted deadfermata EverWhatever202 Nina_slina sufstevens PrecariousLettuce muchKnit Danominator FederalHovercraft365 degauss_me COverbuary british_boondog WorkAccount82 OkYogurtcloset8844 ArtVandelay_90
Full reaction: organizedrobot Wise_Cranberry_1733 noteworthytaco hellogoodbyegone

Balinese

No reaction: agia9891 Proud_Performance307 massy1428 dreadfulrobot
Reduced reaction: -Penny_Lane-
Full reaction: happy_sweet_potato hamburglin hazaali2

There are a few considerations to keep in mind when interpreting these numbers.

First, I was very conservative with what I coded as No Reaction, so the allergic reactions catalogued in Reduced Reaction are often very mild. To illustrate, here are two random examples coded as Reduced Reaction:

“One of my friends is allergic to cats. He came over. It was over an hour before he started getting watery eyes. So that’s just an anecdotal experience. It never got worse than watery eyes.”
“Yes we have a Siberian forest cat and my husband is allergic and with ours he’s not had a bad reaction, but after he pets him he washes his hands so when he wipes his eyes they won’t itch . Because when he didn’t wash his hands before they itched that’s the only reaction he had.”

They're not all this mild, but they're generally closer to No Reaction than Full Reaction.

Second, I do worry that there's a selection effect in terms of who comments on these Reddit posts. Consider two hypothetical cat fanciers:

A. investigates getting a Siberian, finds a dramatic reduction in allergic symptoms relative to normal cats when visiting a breeder, and then gets a Siberian
B. investigates getting a Siberian, experiences normal-severity allergic symptoms when visiting a breeder, and then doesn't get a Siberian

I suspect that Cat Fancier A is more likely to comment on posts in r/SiberianCats than Cat Fancier B, so that the allergenicity of these hypoallergenic breeds will end up underestimated by this methodology. I don't have any way to determine the extent of this bias, but I don't believe that it's the dominant contributor the the observed effect; I still believe that both Siberians and Russian Blues are significantly hypoallergenic.

Third, it's a bit challenging to interpret the data points that required an adjustment period, because there are are at least three potential explanations:

The cat owner's immune system becomes accustomed to the cat’s allergens
The process of moving to a new home is stressful for the cat, the cat produces more Fel d 1 in the wake of the move, but Fel d 1 levels eventually normalize and the cat ceases to be strongly allergenic
The cat arrives covered in allergens produced by other cats, or from other allergen sources at the breeder/shelter, but after a few weeks/months those dissipate

(1) isn't sufficient for my purposes (hosting allergic friends), while (2) and (3) are both fine. Unfortunately, I don't see a way to determine the relative importance of each of the three explanations.

Fourth, many Redditors are inclined to confuse “looking like a [cat breed]” and “being a [cat breed]”. This is especially pernicious for Russian Blues, for which the differences in appearance from non-pedigreed solid blue domestic shorthairs are quite subtle. For this reason, I excluded comments that mentioned cats adopted from shelters, but I don't expect that that filtered out all cases of mistaken breed.

As with interpretation of the data for hypoallergenic cats, there are a few things to keep in mind.

First, many people who feed their cats anti-cat allergen antibodies also take other measures to reduce allergen load. This is because, when they get the cat, the previous caretakers typically didn’t feed the cat anti-cat allergen antibodies, so the cat will produce allergens while the antibodies take effect (a few weeks or months). For this reason, I excluded comments that indicated that the owners had continued to use e.g. anti-allergen sprays through the time the assessment was made.

Second, the same concerns as in footnote 3 around selection bias appear, but are exacerbated by worries about astroturfing. A number of SaFeline Pet reviews in particular come from accounts with no other comment history. Some of these were excluded because they didn't explicitly claim personal experience with SaFeline Pet, but two of them did claim personal experience with SaFeline Pet and I included them despite my concern. Downweight accordingly.

Third, because these anti-cat allergen antibodies take time for their effect to begin, it’s difficult to distinguish between normal adaptation and effective use of antibodies. To our previous reasons for the existence of an adaptation period, we add the antibodies:

The cat owner's immune system becomes accustomed to the cat’s allergens
The process of moving to a new home is stressful for the cat, the cat produces more Fel d 1 in the wake of the move, but Fel d 1 levels eventually normalize and the cat ceases to be strongly allergenic
The cat arrives covered in allergens produced by other cats, or from other allergen sources at the breeder/shelter, but after a few weeks/months those dissipate
Anti-cat allergen antibodies eliminate the allergens produced by the cat

Enough of the comments regarded the allergic responses of guests for me to continue to belive that these work, but the evidence isn’t uniformly unequivocal.

Allergy Defender

Reduced Reaction: lld287 Prestigious-Ad-187
No Change:

Allerpet

Reduced Reaction: Far_Lab6576 sarahieberrie panicky-pandemic apusatan iPetBees
No Change:

Allersearch ADMS

Reduced Reaction: lld287 Gabzalez Onlykitten suzystumpjumper
No Change: t3ch1t Iheartpuppies04 schradem

Live Pure

Reduced Reaction: Leather_Newspaper937
No Change:

Pacagen

muzak and potatoes

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