Loratadine is probably fine because it’s a second gen antihistamine. I just avoid anti-inflammatory (ibuprofen and naproxen) as well as first gen antihistamines like Benadryl or Pseudoephedrine because they can contribute to ED and might counteract these meds to some degree (how much I don’t know.) An erection is a essentially a “swelling” so to speak and both of those reduce swelling.
There’s a phenelephrine nasal spray that I like to use for localized effect on the nose. (It’s just antihistimine.)