AFAIK, the following (possibly wrong!) points seem to summarize the use of the letter h in Italian:
In Italian the letter h (commonly known as
accabut also known as
acca muta) never produces a sound of its own. According to Wikipedia, the letter h used to be pronounced as a slightly aspirated h in most if not all words in Latin (with possible exceptions made for words where the h is both preceded and followed by a vowel), but such pronunciation is lost in modern Italian.
Whenever the letter h appears in a medial position within a word which is not a loanword (e.g. some extremely infrequent foreign words from French, German, etc...) it always affects the pronunciation of the letter immediately preceding it which must necessarily be the consonant c (which must appear as part of one the syllables
chi) or the consonant g (which must appear as part of one the syllables
ghi), with a few exceptions (e.g. I was able to find the words
ohimèin the Treccani online dictionary).
Whenever the letter h appears as the first letter of a word, the h does not affect the word's pronunciation. The only possibilities here are loanwords (several of which have been borrowed from English), plus four exceptions, all of which happen to be indicative mood present tense conjugated forms of the verb
avere(to be), namely the words:
ha(he/she/it has), and
hanno(they have). There seem to be no other exceptions in this case.
Whenever the letter h appears as the last letter of a word, the h may or may not have an effect on the pronunciation of preceding letter, which in this case must always be a vowel. examples are:
beh(alternative spelling of the word
boh, and possibly others.
So, what I want to know is:
Is this list correct, or is something still wrong?
If correct, then what is the complete list of possible "exceptions" and "possibly others" as listed above?