There are a few different ways to find inactive ingredients of a medication. My absolute favorite by far only works for pills, but I always check it first. It’s a brand new search engine from the NIH called Pillbox. In fact, it’s so new it’s still in beta stages.
This search engine is intended for identifying “mystery” pills, but I’ve been using it to get a quick list of every manufacturer of a particular drug and the inactive ingredients.
Here’s a brief tour:
Go to http://pillbox.nlm.nih.gov/ and click on Advanced Search (picture on the right).
In “Drug Name,” enter the name of the drug you’re looking for. In this case, I’ve entered cephalexin, the generic name of Keflex. This will give me both the brand-name drug and all generic variants. Click Search.
The search results will give you a listing of all known manufacturers and dosages of the drug, with the inactive ingredients listed right on the page. You can click hide/show next to “Inactive Ingredients” to see the full listing.
If I can’t find what I’m looking for on this search engine, or need more details, my next go-to search engine is NIH’s DailyMed database, which is an archive of package inserts for all kinds of medication and medical supplies.
For each med listed on DailyMed, there should be an “ingredients and appearance” section on the bottom.
The inactive ingredients should be listed in this section.
Corn Allergy Girl 
Hello, I am not allergic to corn, but I am to Red Dye 40. I have not idea how I hit upon your page, but the information on the NIH “Pillbox” was a God send tonight. The antibiotic ordered for me has red dye and the doctor’s office is gone for the weekend. I researched the medication and between the pharmacist and myself we found a replacement. A white tablet of the same medication at a higher dose, but I will be able to cut it to the correct dose.
Thanks,
MCP
It should be noted that manufacturers can CHANGE their inactive ingredients. Your sites are excellent for research but I always ask my pharmacist to show me the manufacturer’s product insert to check the inactive ingredients. I have a severe allergy to milk proteins and this can be (not always, unfortunately!) a lifesaver.
I am looking for a MS drug that is safe. Do you know anything about Disease Modifying Drugs (DMD)? I’m trying to research all the inactive ingredients and was just wondering if there is already a list?
Thank you!
The NIH pillbox site was retired. The info is no longer being updated.
I know. I’m working on a search engine in my spare time, which is to say I barely have 100 lines of code written.
So now it’s just the backup method, searching through DailyMed haphazardly. Sorry. If you know anyone that wants to work on an opensource project, I’m writing it in Elixir/Phoenix.