Bismillah wa salatu wa salamu ala rasullalah.

1) It is permitted for shias which are addicted to opium, to consume it during the fast.

Fatwa of Grand Ayatollah Jafar Sobhani.

In his book “Rasail tawdih al masail” (p 315), this shia scholar said:

ترياك كشيدن حرام است و اشخاصى كه معتاد به كشيدن ترياك هستند و نمى توانند ترك كنند و با اين حال نمى توانند روزه بگيرند مى توانند به مقدار دفع ضرورت ترياك بكشند، و روزه را واجب است بگيرند.

Translation:

(Issue 1258) Smoking opium is Haram and people who are addicted to opium and find it hard to leave and in such condition can not fast they can just smoke an amount to eleminate their need and should continue their fast as it is obligatory.

2) You are thirsty? No worries, drink some water.

Grand Ayatollah Zanjani in a new Fatwa said: “Reliable report from Ammar and Mufadal bin Umar from Imam Sadiq (as) in Chapter 16 «Whose fast is valid»of Wasail Shia states that those who fast but can’t tolerate the thirst can drink a little bit of water to quench the thirst and in this case their fast doesn’t become void”.

“با استناد به موثقه عمار و روايت مفضل ابن عمر از امام صادق^(ع) كه در باب ١٦ وسائل الشيعه از ابواب “من يصح منه الصوم” آمده است، كساني كه روزه مي گيرند ولي تاب و تحمل تشنگي را ندارند، فقط به اندازه اي كه جلوي تشنگي شان را بگيرد مي توانند آب بنوشند و در اين حالت روزه شان باطل نبوده و قضا هم ندارد.”

Official site of ayatollah:

http://bayatzanjani.net/fa/news/article-340.html

Other links:

http://www.peigham.ir/shownews.aspx?id=836

http://www.entekhab.ir/fa/news/120683

Permitted to drink some water, and smoke opium! WHAT IS NEXT?