I am allergic to this medicine.
al-LER-ji-ko — stress on the second syllable. The 'gi' is like the 'j' in 'jelly'.
Always say this before any prescription or treatment. Show the medicine package if you have it. Critical patient safety phrase.
'Sono allergico' uses 'essere' (to be). The adjective 'allergico' changes by gender: 'allergico' (male), 'allergica' (female). 'A questo medicinale' means 'to this medicine'. You can substitute the medicine name directly: 'Sono allergico alla penicillina.'
Sono allergica alla penicillina.
I am allergic to penicillin. (female speaker)
Change ending to '-a' if you are female
Ho un'allergia ai farmaci antinfiammatori.
I have an allergy to anti-inflammatory drugs.
Use 'allergia' as a noun for broader categories
Ho avuto una reazione al farmaco.
I had a reaction to the medication.
Use when describing a past allergic episode
In Italy, pharmacists ('farmacisti') are highly trained and can substitute branded medicines with generics ('equivalenti'). Always carry a written list of your allergies in Italian when travelling. 'Codice esenzione' on your health card may entitle you to free medications for chronic conditions.