A number of medications (IV meds, pills, and especially liquid meds) contain citric acid or citrate compounds as preservatives. Many meds also contain ingredients such as corn starch, potato starch, or soy lecithin that are derived from citric acid-containing foods.
Make sure to talk to a pharmacist about all the ingredients before you take anything! If you encounter ingredient issues, have the pharmacist check the ingredients of both the brand-name and generic forms of the medication. The active ingredients will be the same, but the inactive ingredients are different, and one of them may be safe to use.
If you still have ingredient issues, look for a compounding pharmacy. These pharmacies will be able to compound your medication with inactive ingredients that are safe for you. I have all of my oral medications compounded with spelt flour as a filler, and have topical medications compounded with Aquaphor Healing Ointment.
Medications aside, something else you need to watch out for in the medical world is blood. Citrates are used as a preservative and anticoagulant in nearly all units of donated blood, which is bad news for us ninjas! If you’re having surgery or may need a transfusion for some other reason, talk to your doctor about this as soon as possible.