Can You Use Cortisporin If You Have A Sulfa Allergy?
In our latest question and answer, the pharmacist discusses whether or not Cortisporin is safe if you have a sulfa allergy.
Can you take Cortisporin if you have you are allergic to sulfa? Thanks!
Drug allergies are of serious concern, and accidentally using or taking something you are allergic to can have dangerous consequences. An allergy to "sulfa" drugs is one of the most commonly reported.
Unfortunately, stating that you have an allergy to a "sulfa" drug is quite ambiguous and essentially misleading. It is a term used very broadly and if you are sensitive or allergic to "sulfa" drugs, it doesn't mean that you cannot use anything that contains sulfur.
Cortisporin (Hydrocortisone; Neomycin; Polymyxin B) does have sulfur-containing compounds (both neomycin and polymyxin B are sulfate salts), but this doesn't necessarily mean you will be allergic to it, even if you have had issues with other "sulfa" drugs.
What Is "Sulfa"?
Sulfur is a chemical element (you may remember it as element number 16 on the periodic table) and is the fifth most abundant element (by mass) on Earth. It is essential to our health and well-being.
It is a necessary component of numerous vitamins (including biotin and thiamine) and is also present in various amino acids (e.g. cysteine, methionine), the building blocks of proteins.
When we say 'sulfa' drug, what is actually being referred to are specific classifications of sulfur-containing drugs. These drug classes are:
- Sulfonamide moiety-containing drugs
All of the above are grouped together and classified as sulfonamides. Sulfonamides are noted as such for containing a SO2NH2 moiety in their chemical structure. The terms 'sulfonamide' and 'sulfa' are often used interchangeably when referencing drug allergies.
Below are examples of each of the sulfonamides.
These contain the sulfonamide group, directly attached to a benzene ring. The example drug here is sulfamethoxazole, a commonly used antibiotic and one of the ingredients in Bactrim.
These also contain the sulfonamide group attached to a benzene ring but at a different position. The example drug here is Celebrex.
These have a sulfonamide group that is not directly connected to a benzene ring. The example drug here is Topamax (topiramate):
Outside of the three main "sulfa" drug classes, there are other sulfur-containing compounds as well, including:
Sulfites are commonly used as food preservatives and have other commercial applications. Sulfite has the chemical formula of SO3.
Sulfites are found in most wines (technically they are sulfite derivatives; SO2). Sulfites are well known to cause sensitivity in certain individuals but are not considered chemically related to sulfonamide drugs and there is not thought to be any cross-reactivity in terms of allergies between sulfites and sulfonamide drugs.
Among other things, sulfates, which have the chemical formula SO4, are commonly used in pharmaceutical manufacturing to create drug salts.
The salt form of a drug can produce beneficial characteristics (such as improved drug dissolution). Common drugs, like amphetamine salts, albuterol, iron supplements (e.g. ferrous sulfate), glucosamine and morphine all utilize sulfate salt forms.
Although they contain sulfur, they are not considered sulfonamides and there is thought to be no risk of cross-sensitivity if you are allergic to them.
Other Sulfur Containing Drugs
Many other drugs contain sulfur but are not considered sulfonamides.
- Prilosec (omeprazole)
- Zantac (ranitidine)
Like sulfites and sulfates, these drugs are not thought to have a risk of cross-sensitivity with sulfonamides.
When one is classified as having a sulfa allergy, and it is has been reported that nearly 3% of the population has one, it typically is specific to one class of sulfur-containing compounds.
Cross-reactivity between sulfa drugs, and whether or not it exists among the three different sulfonamide classes, is controversial. Some studies suggest there is a risk of being allergic to drugs in different "sulfa" classes while others are dubious of any potential risk.
Most evidence suggests that for the vast majority of individuals, cross-reactivity isn't an issue and if you are allergic to more than one class, it is likely that you are simply more susceptible to drug allergies overall. Nevertheless, if you have had dangerously severe allergic reactions in the past, your doctor may choose to be overly cautious.
What isn't controversial is that sulfates, sulfites, and other simple sulfur-containing drugs are considered chemically unrelated to sulfonamides. They are not thought to have any risk of cross-reactivity. However, one their own, certain people may be sensitive to them (sulfites in wine, for example, can cause itching and shortness of breath in many).
Sulfur In Cortisporin
Cortisporin contains three different antibiotics:
- Hydrocortisone; Neomycin; Polymyxin B
Cortisporin is available in multiple formulations:
- Eye drop suspension
- Ear drop solution
- Ear drop suspension
- Topical cream
Two of the antibiotics in Cortisporin are sulfate salts:
- Neomycin Sulfate
- Polymyxin B Sulfate
The prescribing information for Cortisporin states this explicitly:
"Neomycin sulfate is the sulfate salt of neomycin B and C, which are produced by the growth of Streptomyces fradiae Waksman (Fam. Streptomycetaceae)."
"Polymyxin B sulfate is the sulfate salt of polymyxin B1 and B2 , which are produced by the growth of Bacillus polymyxa (Prazmowski) Migula (Fam. Bacillaceae)."
Neither neomycin nor polymyxin B actually contains any sulfur, but they are both manufactured as sulfate salts, as seen by their molecular structures:
Polymyxin B Sulfate
You can clearly see how these sulfate salts differ from the "sulfa" examples given at the beginning of this answer.
Cortisporin With A Sulfa Allergy?
As discussed above, a drug that contains a sulfate salt isn't technically considered a "sulfa drug", even though it contains sulfur.
There is not thought to be any allergic cross-sensitivity between drugs that contain sulfate salts (like Cortisporin) and the sulfonamides (sulfonylarylamines, nonsulfonylarylamines and sulfonamide moiety-containing drugs) listed above.
So, for most people, even if you have an allergy to say, sulfonamide antibiotics, like sulfamethoxazole, there doesn't appear to be a cross-sensitivity with sulfate containing drugs, like Cortisporin.
Nevertheless, there is, of course, the chance you are just allergic to Cortisporin in a way that is distinct and exclusive from your other allergies.
You should always speak with your doctor regarding your drug allergies and appropriate medicine use in your specific medical situation. They may choose a more cautious approach if you have had severe reactions (Stevens-Johnson syndrome) to other drugs in the past.
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