Years ago a chemist in Yecla told me off for saying "aspirina". He told me that aspirin was a trademark and I should ask for ácido acetilsalicílico, salicylic acid. It took me ages to approximate the pronunciation of that mouthful. But I often do as I'm told and, since then, I've struggled to pronounce the generic name every time I buy the stuff in a pharmacy.
Decongestiante isn't that easy to say either but that went well so I asked for a couple of packs of ácido acetilsalicílico de 100 mg. I was asked if I had a prescription. I said no. The chemist told me no prescription no tabs. I've bought those tablets there, in that very chemist, maybe ten times, and across 100 other counters all over Spain for years now. "Can I buy ordinary dose aspirin without a scrip," I asked. The answer was yes, 500 mg tablets don't need a prescription. By now my Spanish fluency had improved significantly. "So I can buy something five times more powerful but not the low dose equivalent? What sort of stupidity is that? We repeated that sort of call and response type conversation for a while - it turns out I know a lot of words in Spanish that translate as terms like madness, stupidity, ridiculousness, silliness and foolishness.
I paid for the decongestant and went to another pharmacy where I bought my low dose salicylic acid.