8. August 2023

Cats are our friends and are often regarded as fully-fledged members of the family. One in three households in Germany has a cat – of which around 30 percent live in a single or two-person household, almost 40 percent in a multi-family household and 67 percent in households with children [1,2].  According to a standardised market research survey, there were over 15 million cats in Germany in 2021 [3].

More cats – more allergies?

As the number of cats in German households continues to rise, so does sensitisation to them – in both children and adults [4]. Common symptoms are allergic rhinitis and conjunctivitis through to asthmatic symptoms or skin irritation, itchy skin, and even itchy palate. Studies show that pre-existing sensitisation increases the risk of developing asthma [5].

However, there are also patients who say they tolerate their own cats: it seems that some cat owners, despite sensitisation, reach a certain level of tolerance when living with their cat. Around 40 percent of people tested for cat allergy want to continue living with their cat despite their symptoms, such as allergic rhinitis [6/7]. Education about possible progression of allergic disease to allergic asthma should be standard. Anyone who has allergic asthma symptoms with dry cough and audible breathing after being in contact with a cat should always consult an allergist or lung specialist. The current German guidelines for allergy prevention advise families where the parents have allergies to not get a cat for the first time while their children are still young [8].

A specialist uses various methods to diagnose a cat allergy. What is important to know in this regard: a cat allergy can develop even if you do not own a cat. What all affected have in common, however, is that they have obviously come into contact with cat allergens – be it on the bus, train, in the office, at home or when trying out a new couch. There are many ways how this can happen [9].

Cat allergens: origin, impact and prevention

Allergens are proteins which most commonly originate from pollen in the air. But also in dust mites, their excrements or even in animal hair. So far, eight different allergens have been found in cats. Of these, Fel d 1 (Felis domesticus) is the most common and important biomarker – it is the most likely to trigger an allergy and is responsible for the disease in up to 95 percent of all cat allergy sufferers. [9].

Air purification and cat washing

While country cats often roam about outdoors and are exposed to allergen-regulating dirt, the “clean” indoor cats often live in rooms that are excessively clean rather than hygienic. This leads to a much higher exposure to allergens. Fel d 1 allergens are found on textiles, furniture and everywhere else in homes occupied by cats. Often long after they have moved out. Besides cleaning textiles with detergents in a washing machine, it helps to also dry them in a tumble dryer.

Washing the cat itself can also significantly reduce the amount of allergens, but is not really a solution with lasting effect and must be repeated weekly.

Using air filtration devices is advisable against so-called indoor feline asthma, provided the devices are equipped with a HEPA filter [10/11].

What chicken egg yolk has to do with Fel d 1

Researchers have found that chickens that come into contact with cats can develop their own antibodies against the cat allergen. These antibodies are found in high concentrations in egg yolk. If the “chicken egg yolk antibody” is added to the cats’ kibble, it can be effective in reducing or eliminating the spread of cat allergens. This blocks the cat allergen in the cat saliva, rendering it completely harmless. In a Purina study, it was shown that the active cat allergen was reduced by 47 percent on average after three weeks of feeding [9].

Cat vaccination: Solution for the future?

Swiss researchers explored the idea of vaccinating cats with virus-like particle technology with the aim of introducing neutralising anti-Fel d 1 antibodies into the cat to reduce the amount of allergens excreted. No side effects were documented. This would make it possible to caress the cat again without it resulting in increased sneezing. But there are ethical concerns against this approach – especially as regards the benefits for the cats [12].

So far, it has not been possible to create a hypoallergenic cat that is more or less “Fel d 1 -free”: Even hairless cats expose their surroundings to large amounts of allergens via their saliva [13/14]. British shorthair cats are said to spread fewer allergens because of their hair length; Siberian longhair cats are considered to be low allergenic despite their long fur [9].

Does iron deficiency lead to cat allergy?

Recent findings show that dietary deficiencies contribute to the atopic phenotype of a person with allergies. Iron and zinc deficiency in particular, but also folic acid deficiency. Often there is no pronounced anaemia, but a functional iron deficiency in the immune cells. This intracellular iron deficiency can be compensated and the natural regulatory function of immune cells can thereby be corrected [15].

From farm to lozenge

The recent findings about the iron utilisation disorder in combination with the well-known farm effect against allergies (hygiene theory) have led to our own efforts to develop a lozenge [16]. In a double-blind placebo-controlled study for pollen allergy as well as in studies in the allergen exposure chamber of the ECARF Institute GmbH on the premises of the Charité university hospital in Berlin, it showed to be effective against house dust mite rhinitis [17]. The efficacy of this dietary approach produced highly clinically significant improvements. The results of a subsequent open-label pilot study in patients with allergic rhinitis caused by cat allergens were also convincing. Trials were conducted to demonstrate the clinical efficacy of allergen non-specific targeted micronutrition in people with cat allergy using holoBLG lozenges (immunoBON®): a 40% reduction in symptoms during allergen provocation was already measurable after three months [18]. Dietary measures can therefore correct an existing cat allergy.


Press contact:

Stefanie Link – Head of Communication
ECARF, Robert Koch Platz 7, 10115 Berlin
T +49 (0)30 857 48 94 25 / M +49 (0) 151 227 808 11



The non-profit foundation ECARF is committed to improving medical care for people with allergies. The foundation’s mission is to make a significant contribution to improving the lives of people with allergies through continuous research and comprehensive education. ECARF Institute GmbH is tasked with implementing the foundation’s objectives. It operates the worldwide unique ECARF allergen exposure chamber, conducts scientific studies and advises companies on allergy-related matters. It also tests products and services according to stringent scientific quality criteria and awards the ECARF Seal of Quality for Allergy Friendliness if the criteria are met.

Source reference

[1] Volsche S. Pet Parenting in the United States: Investigating an evolutionary puzzle. Evol Psychol 2021;19:14747049211038297

[2] Industrieverband Heimtierbedarf e.V. IVH. 2022. Der Deutsche Heimtiermarkt (The German Pet Market, German version only). www.ivh-online.de/ der-verband/daten-fakten/der-deutsche-heimtiermarkt.html; Version: 6/6/2023 www.statista.com Download 04/2023

[3] dpa. Eine Million mehr Haustiere in der Pandemie (A Million More Pets in the Pandemic, German version only). Zeit Online, 22 March 2021. www.zeit.de/news/2021-03/22/eine-million-mehrhaustiere-in-der-pandemie?utm_referrer=https %3A%2F%2Fwww.google.com%2F; Dated: 6/6/2023https://www.dustri.com/nc/de/article-response-page.html?artId=189013&doi=10.5414%2FALX02295.

[4] van Hage M, Kack U, Asarnoj A, Konradsen JR. An update on the prevalence and diagnosis of cat and dog allergy – Emphasizing the role of molecular allergy diagnostics. Mol Immunol 2023;157:1-7

[5] Simoneti CS, Ferraz E, Menezes MB, Icuma TR, Vianna EO. Cat ownership is associated with increased asthma prevalence and dog ownership with decreased spirometry values. Braz J Med Biol Res 2018;51:e7558

[6] Wambre ER, Farrington M, Bajzik V, DeBerg HA, Ruddy M, DeVeaux M et al. Clinical and immunological evaluation of cat-allergic asthmatics living with or without a cat. Clin Exp Allergy 2021;51:1624-33

[7] Buyuk Yaytokgil S, Metbulut AP, Ginis T, Toyran M, Civelek E, Dibek Misirlioglu E. Cat allergy in children and the effect of the COVID-19 pandemic. Allergy Asthma Proc 2022;43:e31-9

[8] Kopp MV, Muche-Borowski C, Abou-Dakn M, Ahrens B, Beyer K, Blumchen K et al. S3 guideline Allergy Prevention. Allergol Select 2022;6:61-97

[9] Jensen-Jarolim E, Jensen SA, Bergmann KC. Allergy to the cat – from diagnosis to management. Allergo J Int 2023;32:130-7 https://doi.org/10.1007/s40629-023-00254-9

[10] Choi YJ, Seong S, Lee KS, Lee K, Seo H, Oh JW. Effects of mechanical washing and drying on the removal of pet allergens. Allergy Asthma Proc 2022;43:e25-e30

[11] Gherasim A, de Blay F. Does air filtration work for cat allergen exposure? Curr Allergy Asthma Rep 2020;20:18

[12] Thoms F, Jennings GT, Maudrich M, et al. Immunization of cats to induce neutralizing antibodies against Fel d 1, the major feline allergen in human subjects. J Allergy Clin Immunol. 2019;144(1):193‐203. https://doi.org/10.1016/j.jaci.2019.01.050

[13] Dance A. The race to deliver the hypoallergenic cat. Nature 2020;588:S7-9

[14] Buckley RM, Gandolfi B, Creighton EK, Pyne CA, Bouhan DM, LeRoy ML et al. Werewolf, There Wolf: Variants in hairless associated with hypotrichia and roaning in the Lykoi cat breed. Genes (Basel) 2020;11:682

[15] Roth-Walter F, Afify SM, Pacios LF, Blokhuis BR, Redegeld F, Regner A et al. Cow‘s milk protein beta-lactoglobulin confers resilience against allergy by targeting complexed iron intoimmune cells. J Allergy Clin Immunol 2021;147:321-34 e324

[16] Pali-Scholl I, Bianchini R, Afify SM, Hofstetter G, Winkler S, Ahlers S et al. Secretory protein beta-lactoglobulin in cattle stable dust may contribute to the allergy-protective farmeffect. Clin Transl Allergy 2022;12(2):e12125

[17] Bergmann K, Graessel A, Raab J, Banghard W, Krause L, Becker S et al. Targeted micronutrition via holo-BLG based on the farm effect in house dust mite allergic rhinoconjunctivitis patients – first evaluation in a standardized allergen exposure chamber. Allergo J Int2021;30:141-9

[18] Bergmann KC, Raab J, Graessel A, Zwingers T, Becker S, Kugler S et al. The holoBLG lozenge reduces symptoms in cat allergy – evaluation in an allergen exposure chamber and by titrated nasal allergen challenge. Clinical Translational Allergy 2023, in press