The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 78

91. How long should it take to know if a medication is working?

  • This topic is controversial and how long to trial meds is not agreed upon. It varies by provider. This is because there haven’t been many studies done on how long it takes to see therapeutic effects in mast cell patients.
  • Firstly, this question is not “how long does it take for a medication to become active after I take it.” This question is how long you should keep taking a new medication to see if it helps your disease.
  • Firstly, when you are trialing a new medication, or even a new medication dose, try as hard as possible to not change anything else at the same time. It is easier to do this for medication that has short term benefits. I realize this is not always possible, and when it is, it is still a pain.
  • However, you really do need to be able to tell if any changes that occur are from the medication change or not. For example, if you are trying a new antihistamine, and two days after you start it, you also increase your dose of another med, and two weeks later you feel better, you are going to have no idea if it was the new antihistamine or the dose increase of the other med that helped.
  • In my experience, this leads to people being on a ton of meds that don’t all help. Some of us are on a ton of meds that actually help and that can’t always be prevented, but a lot of people just keeping adding things on top of one other without being sure they help. This can really complicate things down the line.
  • How long I trial meds has always been determined by how long it takes for them to cause notable changes in clinical symptoms. Because there aren’t a lot of studies on this topic in mast cell patients, it is common to use recommended time frames found in literature for other cells or other diseases.
  • If they have immediate short term benefits, I trial them for two weeks. Medications that block mediators from acting, like antihistamines and leukotriene inhibitors, are in this group.
  • If they have moderate term benefits, I trial them for six weeks. Medications that prevent mediators from being made, like COX inhibitors for prostaglandins or 5-lipoxygenase inhibitors like zileuton, are in this group.
  • If they have long term benefits, I trial them for sixteen weeks. Mast cell stabilizers like cromolyn and ketotifen and biologics like anti-IgE therapies are in this group.
  • If meds have mixed term benefits (like short term and long term effects), I trial them for the longer term.
  • Please note that steroids are a special case here because they have so many effects that are short, moderate and long term. People generally see immediate relief from them but they really are not meds that should be taken regularly if it can be avoided due to the slew of dangerous side effects.
  • These time frames have been recommended to me by my care team but you will need to discuss this with your own care team. I have found literature supporting these time frames necessary to produce clinical changes in other cell types or diseases.
  • I would also like to mention that in the past, I thought that four weeks was the appropriate period for trialing meds with short term benefits like antihistamines. I now feel that a two week trial is sufficient to identify benefits from these meds.
  • Please also note that for advanced systemic mastocytosis, including aggressive systemic mastocytosis and mast cell leukemia, there have been studies that have identified optimal duration of therapy to see a response for interferon and chemotherapies.