Sorry but I had to ask because there are a lot of words where you have to use the back on your tongue and throat (carro, arroz, etc), and also a lot of words that you have to pronounce with a nasal sound (pão, cão, etc). So if your sinuses are congested or your throat is irritated doesn’t that makes it harder to produce the sounds?. In spanish we use more the tip of the tongue and nasal sounds are not common unless you use the letter “ñ” for example año, baño, añil, etc.
A fun question, @edil.cajigas 
The nasal sounds are difficult when you’re completely clogged up! Otherwise, I don’t personally feel that it’s inherently harder than other languages.
Não, seriously… I’m having a hard time pronouncing words like carro, árroz, roxo, cor-de-rosa. Here where I leave there are people in some areas that pronounce those words that way (carro and arroz are the same thing in spanish), and we said that they talk with “frenillo” (lingual frenulm breve), not because they have any physical condition but because that’s their accent. I wonder if there are parts of Spain that pronounce those words that way.
@edil.cajigas, if it helps, it’s acceptable in Portugal to roll the Rs like Spaniards do, instead of making the harsh throaty R. Both variations are common in the country!