Answer

There is no known interaction between Zyrtec (cetirizine) and Buttercup syrup (which contains two active ingredients, capsicum, and squill). They are considered safe to take together.


What Is Buttercup Syrup?

Buttercup Syrup is a brand name cough medication available in the UK and contains two active ingredients:

  • Squill
  • Capsicum tincture

The bulb of the Squill (Urginea indica) plant is used medicinally for its stimulant, expectorant and diuretic properties. Squill has numerous constituents that are thought to be responsible for its effects, including:

  • Glucosidal substances (e.g. scillitoxin, scillipicrin and scillin)
  • Calcium oxalate
  • Cardioactive glycosides (e.g. bufadienolides, scillaren A, and proscillaridin A)

While generally considered safe in small amounts, there is some concern that squill can exacerbate certain cardiac conditions as it contains cardiac glycosides.

In addition to squill, buttercup syrup also contains capsicum tincture, commonly known as a red pepper extract. Capsicum is used for a variety of indications and is most often applied topically for its pain-relieving effects.

Capsicum is classified as GRAS (generally recognized as safe) by the FDA.

Neither squill nor capsicum are known to interact with Zyrtec (cetirizine).


What Is Zyrtec?

Zyrtec (cetirizine) is a "second-generation" antihistamine, indicated for the treatment and prevention of perennial allergies, seasonal allergies and hives.

Zyrtec has a higher incidence of sedation than other second-generation antihistamines, such as Allegra (fexofenadine) and Claritin (loratadine), but is still far less sedating than first-generation antihistamines (such as Benadryl).

Zyrtec is most often dosed once every 24 hours and has an onset of action around one hour.


Summary

  • There is no known interaction between Zyrtec (cetirizine) and Buttercup Syrup (squill; capsicum tincture). They are considered safe to take together.

  • References
    1. Clinical experimentation with a cardiokinetic extracted from squill: 3-beta-ramnoside-14-beta-hydroxy-delta-4,20,22-bufatrienolide (proscillaridine A)]. PubMed
    2. Urginea maritima (squill) toxicity. PubMed
    3. [Effect of proscillaridin-4'-methylether on pressure rise velocity in the left ventricle of patients with coronary heart disease (author's transl)]. PubMed