This in turns makes me miserable - I'm not saying it's mental health, but it affect my mental wellbeing, and means I'm essentially covering 2 people's work quite a lot of the time. As part of 'reasonable adjustments', I take back some of my colleague's work when they're feeling anxious - but I feel that my own mental health is being totally disregarded. I've also had both colleague's (and some other junior members of the team) calling in sick several times over the last few months.
YANBU @LadyGodiva4
Both your colleagues sound in denial about trying to manage their health conditions. It is not fair that your health suffers. I have been in a similar situation - colleagues in denial about the impact their illness has on others, and expecting the work-horses to shoulder extra load.
You're going to have to seek help to stop this situation. It isn't cruel or unfeeling if you do it properly.
You probably need to try a few strategies: regular monitoring of their productivity, for example, and discussions with them about their level of sick leave. Is their lack of productivity damaging the business?
Also , do you report to a manager ? They should be helping you with apportioning workload appropriately.
Are either of your colleagues so ill as to require 'reasonable adjustments'? It might be that they are not capable of a full-time workload, so part-time work might be more appropriate. Of course, there's an issue there that it's also a part-time salary!
Are there other less drastic reasonable adjustments, such as staggered starts? or flexible working? Some people with a depressive illness find starting early difficult and might be better working 10am to 6pm, or something like that, if it's possible.
"Flexitime" working can be done with proper time keeping over, say, a fortnightly time period - when your colleague/s are feeling OK, they put in longer hours, and then when they are unwell, they can take an afternoon out, or whatever.
Good luck! You'll have people telling you you're being discriminatory, but businesses have to be managed and the whole workload falling on you is also unacceptable.