I've just started on letrozole a month ago on Sun brand and after reading all the experience of ladies on here, I tried to check exactly what the differences are between the various brands. It is possible to check the detailed ingredients (active (letrozole) and inactive/excipients) by looking at the 'summary of product characteristics' which is available from the manufacturers and what is held by the licensing authority.
There are a couple of key points;
1.Cipla and Teva both contain tartrazine, but the others don't. Others use iron oxide yellow for colouring. Cipla also has iron oxide red as well as iron oxide yellow. None of the others do. These two brands are the most different from Femara original.
2. Sandoz and Femara (Novartis) look identical across all ingredients.
3. Accord and Zentiva are essentially identical to Sandoz.
4. Sun Pharma is almost the same as Sandoz except for Sun contains PEG (water soluble binder ) and povidone ( a water soluble stabiliser) . Both these are very common stable additives, non-toxic, without any particular SEs
5. Actavis is almost the same as Sandoz except it contains polyvinyl alcohol - a water soluble, stable, commonly used non-toxic additive in the coating.
Seems that many complaints in UK about Cipla brand and Sandoz brand is popular.