Is complaining considered a lack of faith? Many times when I personally have problems I pray to Hashem for some kind of relief but when I’m not answered I end up complaining out of distress to friends and family. An example I can give is the following; I have a slow thyroid for which I must take hormones every day. The condition makes you tired and listless even with the medication sometimes (alot of times actually.) For many years I tried to ignore the problem and go about my business only praying to hashem for relief which I’m still waiting for. But sometimes I complain to my friends because it so distressful to me and I’m wondering if this is a sin.

It is unfair for someone that doesn’t suffer to answer such a question. In any event – complaining is not a recommended way to approach difficulties in life. A difficulty is a challenge. We don't ask for any challenges like that but if they do come upon us we should treat them as such. It's a challenge from Hashem to find our connection and establish a closer relationship with him, better be afflicted by G-d than neglected by G-d. Our prayers are always heard (Olat Reiya Rav Kook) though not necessarily fulfilling what WE wanted it to fulfill, Hashem cherishes all of our prayers and uses them in the best way for us, sometimes the fact we were not answered the way we want is so we should pray more, sometimes there are reasons we can't think of but we must not stop to pray. I wish you health and happiness.