Family planning (trying to fall pregnant, pregnancy or breastfeeding). None of the DMTs have a label that states they are safe and indicated to treat MS in pregnancy. In fact, several are contraindicated in pregnancy. So if you are a woman who wants to start or extend your family you will need to stop these DMTs prior to falling pregnant; these include fingolimod and teriflunomide. On the other hand, several DMTs have a very good emerging safety profile in pregnancy and are increasingly being used to treat MS in women who are planning to fall pregnant. These include interferon-beta, glatiramer acetate, dimethyl fumarate and natalizumab. With the so called immune reconstitution therapies or IRTs, i.e. alemtuzumab, cladribine, ocrelizumab and HSCT you need to wait for your immune system to reconstitute before falling pregnant. For alemtuzumab this is 4 months, for cladribine 6 months and for ocrelizumab 12 months (the US or FDA label states 6 months).
Drug intolerance or adverse events. However, this usually triggers a switch to another DMT rather than stopping the DMT.
Development of another disease or comorbidity. For example, being diagnosed with a cancer and needing treatment for the cancer. The decision to stop a DMT in this situation depends on many factors.
Personal reasons. Some MSers simply decide to stop treatment. It may be due to their disease being stable or perceived lack of effectiveness. It is also not uncommon for some MSers to want to try alternative medicines or adopt a new lifestyle. If you are one of these people I would recommend you continue to interact with your MS team and have regular monitoring (clinical, MRI, PROMS and possibly CSF) of your MS so that if these alternative strategies don't work you keep the option open of going onto a 'traditional DMT'.
Financial (not covered by a national health service or medical insurance scheme, or you can't afford DMTs).
Progressive or more advanced MS. In some countries neurologists stop DMTs in MSers who develop progressive MS or their disability becomes more advanced, for example when you need to start using a wheelchair. This is based on a lack of evidence of the effectiveness of many of the DMTs in MSers with progressive MS or with more advanced disability. Please note I don't agree with this as there is evidence that suggests people with both progressive MS and more advanced disability still benefit from DMTs.
Ageism. Some neurologists recommend stopping DMTs in MSers who reach a certain age. Again this is based on a lack of evidence of the effectiveness of DMTs in this population. I personally don't agree with this.
Stable or inactive MS. Some neurologists stop DMTs in MSers who have been on treatments for many years and their disease is inactive, i.e. no evidence of disease activity (NEDA). There is real-life data that indicates that MSers who stop DMTs in this situation do worse, on average, compared to MSers who stay on treatment. There are clinical trials currently being undertaken to definitively answer this question. These trials are randomising MSers to stay on their DMT or switch to a placebo and to compare how these two treatment groups do.