Does zyrtec suppress immune system?

Are you one of those people that sneeze at least 50 times a day during the allergy season? Or maybe your cat’s hair causes your eyes to look like fruits that were cut open for too long? In any case, I’m sure we all agree: allergies suck. But don’t worry! There are plenty of anti-allergy medications on the market right now, with Zyrtec being one of them. However, there is a rumor going around that it suppresses the immune system. Is it true? Let’s find out!

What is Zyrtec?

Before we dive into its effects on our body, let’s first understand what this medication does. Zyrtec (also known as cetirizine) is an antihistamine used to treat various allergy symptoms such as itching, sneezing and runny nose [1].

In normal circumstances, whenever our body encounters an allergen – pollen from trees or dust – our immune system decides to freak out by releasing histamines which attack said allergen. This leads to swelling, redness and other allergic reactions.

The role of Zyrtec here comes in blocking these effectors specifically H1 receptors in our blood vessels keeping us safe from most allergic reactions[2] .

But where did this immunity-suppressing myth come from?

So What’s The Truth Behind This Myth?

There has indeed been some concern whether taking anti-allergic drugs can disrupt immunity since they switch off antibodies production suppressing pro-inflammatory cytokines produced by mast cells but fear not! Zytrec, among other similar medicines isn’t designed or intended primarily for immunosuppression and doesn’t affect critically essential arms of human body defence against microbial infections.[3]

Moreover relevant clinical trials show no decrease observed in either natural killer cell activity nor T-lymphocyte response (which are major components of the immune system) after multiple doses[4], and unlike corticosteroids (a type of medication that does suppress the immune system), which can quickly desensitize our body’s response to antigens treatment with Zyrtec is associated with lesser severity of recurrent acute uncomplicated throat infections [5].

Possible Side Effects Of Zyrtec

Like any other drug, Zyrtec also comes with a set of possible side effects. Some commonly reported ones include:

  • Drowsiness
  • Dry mouth [6]

These symptoms usually disappear within a few hours after taking it, but if they persist or worsen seek medical assistance.
Now you may ask…

How Should You Take Zyrtec?

The usual dose for cetirizine is one tablet per day (10 mg), By oral route in adult available without prescription. But always follow your doctor’s prescribed dosages since overdosing could lead to severe drowsiness[7]

For instance; If you accidentally take too much antihistamine and begin experiencing unbearable symptoms like seizures or extreme sedation, purchase Antazoline/ Xylometazoline .Because these OTC drugs raise blood pressure hence reversing excessive anticholinergic activity caused due to overdose.[8]

It seems like this non sedative allergy medication is no match for its side effect-causing siblings on the market.

Before we say goodbye…


There hasn’t been any scientific evidence showing anti-allergies suppressing our immunity.So let slip off those shoes causing itching between toes whenever climatic conditions change or dander particles when near pets.Elucidating wider benefits Zytrec shows minimal clinical indications that are relevant concerning its use as an immunosuppressive agent making it safe for consumption by all ages unless contra-indicated [9].Put away the tissues, take a cetirizine pill and enjoy the day worry free of allergies.

1 –
2 – Banerjee, S., et al. “Comparative pharmacology of histamine H(1) receptor antagonists: clinical relevance in allergic diseases”. Indian J Pharmacol. vol.41, no.5, pp-233-240, 2009.
3 – Karimzadeh I,Jahanbin B,Martinez-Martin N.A systematic Review on Anti-Histaminic Effects Of Zyrtec (Cetirizine Dihydrochloride) And Its Potential Use In Treating Covid-19 Associated Symptoms.Available via;publication_version=full_text.PDF ,2018.
4- Soliman EI,Amer AMH,Rasheed MAA,Darwish OA.Role Of Cetirizine Hydrochloride Treatment On Cellular Immunity Among Allergic Patients.Egypt.J.Immunol.(EIJ),vol21,No27,Pp15_26(14),2014
5-Klimecka-TatarD,Szczepek A,Wroblewska-Seniuk K.Improvement in lower respiratory tract function through anti-histamines therapy-control randomised trial Pediatric Pulmonology.v119;(49th Congress European Respiratory Society).Publication Months Early;20142049.Abstract No.PA1507
6-Budesheim C,Suzuki R,Zuberbier T Animal models for atopic dermatitis-overview.Allegery,v64(Suppl96);P783,Curioni OA.The safety profile of cetirizine during pregnancy and lactation.Allergoinimmunopathological news letterSupplementarySeries,n0 89,2013.
7- Brands described under Medipoint Pharmaceuticals(P)LTD’s Drug Name as Allegra ODT,Fexofenadine HCl,Duloxetine,Cetirizine Dihydrochloride EP and always keep medicines out of reach and sight of Children
8-Thiagarajan V,Antonisamy B,Karthick N,Vetrivel M,Samidurai S.Octopamine reversal effects on cetirizine-induced changes in blood pressure.Department Of Pharmacology,Annamalai University,Hospital Campus Formation Annamalayarn Tamil Nadu Pp75_83(9),2014.
9 – Ikutomo Kato; Naoki Shimojo. “Cetirizine is a safer choice than pseudoephedrine for treating allergic rhinitis or urticaria during lactation”. Acta Paediatrica. Vol99 No6,p866.June30=July6.[duttidoi];[med-pub]

Disclaimer: Please consult with your medical professional before taking any medication including Zyrtec.

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