Long periods of Methimazole with Graves and Hyperthyroidism can cause the liver enzymes to rise dramatically and damge the liver.
As for leaving Graves and Hyperhtyroidism untreated...that all depends on the levels ...FT3, FT4, TSH, TSI, TPO.
I ended up with 3 episodes of thyroid storm (atrial Fibrillation) paddles put on the chest to get the heart rythm back on track and 2 leaking valve prolapses.
Also an 'innocent' heart murmur is no longer innocent.
This was ALL before RAI .....tracing Graves and HyperT back to 1985 and RAI done 12 months after diagnosis in 2007.
Dont delay in not treating Graves.....if conventional medicine is not what you want then at least get on Beta Blockers to slow that heart rate down.
You can die from Graves related Hyperthyroidism.
Scary thought... I have had all the symptoms of graves Disease, Hyperthyroid since I was 13 or 14... including the hand and head tremors. A large lump on my throat that as I approached forty was very visible. Always thin unti, about two years prior to my thyroid going wild. I thought I was dying, instead of my hands and head shaking like a person with parkinsons, my entire body shook. My heart was racing at 160 to 170 a minute at times but most always around 140. Looking back, I shutter to think of the harm that was done to my body. Still is, even after taking RAI and a short period of Hypo, I went right back to Hyper. I refuse to do anymore RAI, as it messed my eyes up and I refuse to have it taken out. So far, conventional medicine has not been kind. I wish , looking back, I would have stuck with the methimazole and beta Blockers. Hindsight is always 20/20 now isn't it? Or had been thinking more and tried a more natural approach. I did not educate myself in time and have certainly paid a dear , high price. I am working on it though.
Forgot to tell you I was diagnosed with Graves disease 2 monthes ago. thanks
How long can I let my hyperthyroidism be untreated without complications?
That depends.
If it is transient, or temporary, it may rectify itself.
If you let hyperthyroidism go unchecked for a long period of time it will damage your heart and you will die from one of several causes directly linked to ongoing severe hyperthyroidism.