Many, many medicinal products contain corn derivatives, including herbal medicines/natural health products.
Most pills contain corn starch. It is used to hold them together. Almost all over-the-counter antihistamines are made this way. Cough syrups, antibiotic suspensions and other liquid medications are typically sweetened with corn syrup or thickened with dextrose. Some eye drops are thickened with dextrose, and some creams and lotions contain corn as well, though this is uncommon. Always read the ingredients.
Medication ingredients in Canada follow similar laws to the laws that deal with foods: corn derivatives can go by names that don’t include the word “corn,” including dextrose, glucose, maize starch, hydrogenated starch hydrolysate, and xanthan gum (see also “Sugar Alcohols (Polyols) & Polydextrose used as Sweeteners in Foods,” described more concisely here).
The non-medicinal ingredients of medications for human consumption should be listed on all their packages, but sometimes the ingredients are listed only on leaflets inside the packages. For these medications, you may have to have a pharmacist open the package for you so that you can read the leaflet without causing suspicion.
If your medication is over-the-counter, this is where the story ends, but if you need to know whether there is corn in a medication prescribed for you, there are further hoops to jump through.
The easiest way to avoid problems is to let your doctor know about your corn allergy in advance. This includes letting him or her know all the names that corn derivatives can go by. When you go to the doctor you can then ask him or her to look up the medication he or she is prescribing you in the CPS before he or she writes the prescription. (The CPS — Compendium of Pharmaceuticals and Specialties — lists the medicinal and non-medicinal ingredients of every kind of medication legal in Canada. Every doctor and pharmacist has a copy. These days, copies are almost exclusively electronic, and only pharmacists and doctors can access them. Pharmacy technicians are generally not able to access the CPS). If the drug or brand of drug the doctor had in mind comes in a formulation with corn in it, it can then be possible for the doctor to decide right there to prescribe you a different one.
Make sure that you have your doctor write the brand of the corn-free drug and “no substitutions” on the prescription so that when you take it to the pharmacy, they don’t give you another formulation of the same drug that might contain corn. Alternatively, if the doctor doesn’t have time to look up the drug, make sure that he or she writes “corn-free formulation” on the prescription so that it is clear to the pharmacist that he or she has to look up its ingredients before giving it to you. In this case, you will have to list the names that corn derivatives can appear under to the pharmacist too. If your pharmacist finds that the drug the doctor has prescribed is not available in a corn-free formulation, he or she will have to phone the doctor and get him or her to change the prescription, and then repeat the process if that doesn’t work out. (This is a very annoying situation for everyone involved! Best to avoid this by having the doctor look up the drug in the first place.)
Corn-free formulations of last resort
In the event that the drug that the doctor wants to prescribe for you is not available in a corn-free formulation, it may be possible to phone the drug manufacturer and find out whether they will sell the pure drug to a compounding pharmacy (such as this one, in Toronto). If you don’t feel comfortable doing this yourself, your pharmacist can do it for you. A compounding pharmacy can then take this powder and make it into pills or capsules for you, using a filler other than corn starch, such as potato starch.
- Warning: some compounding pharmacies just crush up high dose pills and add filler to make lower-dose pills. If the original pills contain corn starch, so will the compounded pills, even if the filler is corn-free. Check to see that the compounding pharmacy you wish to use has the capability to make up pills or capsules using pure powdered medications.
Drugs compounded this way can be expensive, but they can be worth the cost if you are going to be taking that particular medication for a long time. If the prescription is for something that you only need to take once or twice, though, it may be easiest just to take the 1 or 2 pills along with an antihistamine, depending on the severity of your sensitivity to corn.
- Bringing in corn-free medications from other countries may also be an option, if you have contacts in other countries who understand those countries’ labelling laws and are careful about reading ingredients.
NEW! As of 2017, Tylenol has released a formulation of acetaminophen capsules that don’t contain corn! I am extremely excited about this opportunity to buy acetaminophen over the counter and at a low cost for the first time in over 25 years!