<s>[INST] My husband drinks coffee most every morning on his way to work using a coffee travel mug with a button release lit. The problem is, I was looking at it this morning and rinsing it, noticed bit of black in mouth piece. This led me to opening the circular release seal and inside it I found slimy black gunk that appeared to be slimy mold. I am very concerned; he has been using this travel mug for some time, months. I have always rinsed and wiped it down believing I was doing the right thing.  Read about it online (reviews) and others posted have found the same issue with horrible black slime coming out when they tore off the bottom.  I am not concerned about the silly mug, we trashed it.  I am concerned however about how this may affect his health.  What can this possibly cause?  I am hoping that the most it could cause would be some stomach and digestive problems, but I am concerned about the fungus or bacteria it has introduced into his system.  Is there anything we can do at home? He is someone that feels he should tough it out and avoids going to a doctor unless he has to even though he has great health insurance.  I would be most grateful if you could ease my mind, I am concerned.  Thank you. [/INST] Hello dear, Thank you for your contact to Chat Doctor. I read and understand your concern. I am Chat Doctor answering your concern. It is likely that this slimy black thing can be fungal or bacterial colony which is posing problem. But it can cause health hazard in the immunocompromised patient. Your husband seems to be a healthy person, so it will not pose any problem to it. But if you are much concern you can wait for the week. If within a week you find something problematic than you can take the treatment accordingly. For the future purpose please do good through cleaning from the mug and avoid the formation of such a problem. Please advice your husband regular exercise early in the morning it will boost up his immunity. So that you will not have to worry about him much. I will be happy to answer your further concern on bit.ly/ Chat Doctor. Thank you, ChatDoctorInfectious diseases specialist, ChatDoctor. </s>