I have been on 100mg Levo + 60mg lio for about 8 years. Last year I had a lot of problems with pharma lio and asked to change to an alternative. It took a time to persuade my gp to agree. He then said he was not allowed to make the change, I had to see an endo. It took three months for an appointment. When I got to the hospital, my appointment had been changed to a student! She was very helpful but was not allowed to order a change or advise me. I don't know why I was seen by her. There was no endo on duty - she was being supervised by a consultant in another specialty. It took several more days but the student did finally get authority to switch my lio to Perigo.
I now get a prescription from my gp for "Perigo ONLY". It took another couple of months for my local Tesco pharmacy to arrange it's import from the States.
My own experience is that T4 alone does not work. I was on only T4 for over ten years and I was never well. After starting T3, I have been a lot better.
It has been a constant battle with gps who insist I should reduce meds - mostly T3 as it costs more. I find if I reduce T3, I get lots of stomach problems - cramps and tummy upsets and a constant severe headache. I'm also really tired. If I reduce T4, I'm really tired but the main problem is my apetite. I'm really starving all the time, constantly eating and my weight goes through the roof.
Whilst I was trying to sort Perigo, I did order lio from Turkey. I found them very helpful but it does take about three weeks to receive the pills. Also there is a minimum order which I think was £70 + postage. That would have lasted me over 5 months. I only actually took them for two weeks. I had no problem with them.
I have learned over the years that I have to fight doctors constantly to obtain the meds I clearly need. Don't accept it when they say you have to reduce or stop meds. It is an uphill battle but unfortunately one we thyroid sufferers have no choice but to fight.