Sesame Oil in Medication: The Newest Major Food Allergen and Your Prescriptions

Sesame is the newest major food allergen in the United States. The FASTER Act, signed on April 23, 2021, made it the ninth, and its labeling requirements took effect on January 1, 2023. But that law covers food, not medication. Sesame oil does turn up in medicine, including as the oil some long-acting injections are dissolved in, and an injection is a medicine whose label you rarely get to read. Here is where sesame appears and how to check.

What the sesame law changed, and what it did not

Since January 1, 2023, every FDA requirement that applies to major food allergens, including labeling, has applied to sesame. A packaged food made with sesame now has to say so in plain language, either in the ingredient list or in a “contains” statement. For people with a sesame allergy, that was a real step forward at the grocery store.

It did not reach the pharmacy. The FDA states that its food allergen labeling requirements do not apply to drugs or cosmetics. Sesame oil may be named in a medicine’s ingredient list, but nothing requires it to be flagged as an allergen. The same gap applies to every major food allergen, which our guide to why medication labels do not have to list allergens explains in full.

Where sesame oil shows up in medicine

One important use is as a vehicle for oil-based injections given into a muscle. Some drugs are dissolved in a vegetable oil so they release slowly from the injection site, and these long-acting oil injections have been used for decades in schizophrenia treatment and hormone therapy. A pharmaceutical review lists sesame oil as the vehicle for some long-acting antipsychotic injections, alongside other oils such as castor oil and cottonseed oil used for other drugs. A clinical review of sesame allergy also lists sesame in some hormone products, and in cosmetics such as soaps and ointments. It is not only injections, though: at least one kind of oral capsule has its drug dissolved in sesame oil, and its prescribing information lists a past hypersensitivity (allergic) reaction to sesame oil as a reason not to use it.

Sesame oil is one of several oils used this way. Peanut oil plays the same carrier role in a few medicines, covered in our peanut and tree nut guide, and soybean oil in others, covered in our soy guide.

How much of a risk is it?

Sesame allergy is estimated to affect roughly 0.1% to 0.24% of the US population. For those people, the grade of oil matters. A clinical review of sesame allergy notes that the refined sesame oils typically used in medications are usually not allergenic, although delayed reactions have been described. Unrefined sesame oil, which is often used in baking, is a different story and has been linked to anaphylaxis.

So the honest answer is “usually fine, not guaranteed.” European regulators land in the same place: their labeling guideline calls for any medicine containing sesame oil, by any route, to tell patients that it may rarely cause severe allergic reactions. US rules have no general requirement like it. If you have a sesame allergy, especially one that has caused a severe reaction, that is worth raising before an oil-based injection, not after.

What if you have reacted to an injection before?

A 2014 review of food-derived ingredients in medicine, published in the Journal of Allergy and Clinical Immunology, reached a balanced conclusion. Most people with a food allergy tolerate medicines containing ingredients from that food, so those medicines should not be routinely withheld. But if someone has an apparent allergic reaction to a medication, a possible allergy to the food component should be investigated.

For sesame, that means an oil-based injection followed by hives, swelling, or trouble breathing deserves a closer look, and the carrier oil belongs on the list of suspects alongside the drug itself. Bring the product name to an allergist. Our guide to whether you are allergic to the drug or the filler explains how an inactive ingredient can turn out to be the cause.

How to check an injection for sesame

Here is the useful fact: for a prescription medicine that is not taken by mouth, federal rules require the label to name its inactive ingredients, and for an injection, to give the quantity or proportion of each one. The few exceptions cover things like flavorings and a plain water base, not an oil. So the oil will be on the vial or carton and in the prescribing information. The information exists; you just have to ask for it.

• Ask the person giving the injection to read you the inactive ingredients from the vial or carton, and to look for sesame oil.
• For a repeat injection, such as a long-acting medicine given every few weeks, make sure the sesame allergy is on your record at the clinic and the pharmacy, and ask again if the product or its manufacturer changes.
• For capsules, ask your pharmacist to check the inactive ingredients for sesame oil as well.
• If you inject at home, read the carton and the package insert yourself before the first dose.
• Do not skip or stop a dose on your own. If a medicine you need contains sesame oil, review it with your prescriber or pharmacist and, for a severe allergy, your allergist.
• Check the product with the app. AllergenMeds flags ingredients like sesame oil in the exact product you look up, so you know what to ask about before your appointment.

This guide is for education only, not medical advice. Always talk to your doctor or pharmacist before starting, stopping, or switching any medication.