The more research I do, the more I realise that there are many people out there suffering with this particular problem. Take a look here: http://www.askapatient.com/viewrating.asp?drug=21124&name=LAMISIL+AT&page=1&PerPage=60
Askpatient.com is a US site, but I have found others here in the UK too. In many of the cases, the patients have recorded that, when they reported the problem to their doctors, the latter were 'unaware' that the drug could cause this particular debilitating side-effect. Now, either that's because the doctors are reading information on the drug which doesn't highlight this problem or they feel that the trade-off for being free of the fungal infection is worth the reported three month's duration of taste loss. However, the majority of online reports I have read (like the one above), record patients as saying that if they'd known about the severity and duration of this problem - and the possibility that their taste may not return at all they would have tried an alternative to Terbinafine.
If you read the reports on the above site, you will see other 'side-effects' which are also not at all pleasant for those suffering them.
An interesting piece of information here: http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/022071s007lbl.pdf
contains the following : 5.2 Taste Disturbance Including Loss of Taste
"Taste disturbance, including taste loss, has been reported with the use of terbinafine. It can be severe enough to result in decreased food intake, weight loss, and depressive symptoms. Taste disturbance may resolve within several weeks after discontinuation of treatment, but may be prolonged (greater than one year), or may be permanent. If symptoms of a taste disturbance occur, Lamisil Oral Granules (Terbinafine base equivalent) should be discontinued."
You'll note that it states that "taste disturbance may resolve within several weeks [after discontinuation], but may be prolonged (greater than one year), or may be permanent".
Which is somewhat different from the patient advice leaflet (included with each box of tablets) which states, under Possible side-effects, "Uncommon (occur in less than 1in 100 people) -- Taste loss or altered taste which usually disappears when you stop taking these tablets. However, a very small number of people (less than 1 in 10,000) have reported the taste disturbance lasts for some time and as a result they they go off their food and lose weight".
The inferrence in the latter is that the taste loss will be gernerally resolved (immediately?) upon stopping the tablets. And that 'taste disturbance' could in extreme cases last for some time. How long is some time?
Both these instances give no measurable definition of the time one will be without taste. I believe this failure to adequately specify even a minimum time period is a failure to warn patients (and doctors?) sufficiently for them to make an informed decision on whether or not to take (prescribe?) the drug.
Watch this space, folks.