Can You Take Lasix If You Are Allergic To Sulfa?

Answer

Thanks for reaching out to us! Evidence is mixed regarding whether or not having a 'sulfa' allergy precludes you from being able to take Lasix (furosemide).

If you take a look at the chemical structure of Lasix, you will see that it contains a sulfa moiety, as shown in the picture below:

Since furosemide does contain a sulfa element, there is a theoretical risk of cross-sensitivity in those who have an allergy to sulfa antibiotics. The prescribing information for furosemide warns as much:

Patients allergic to sulfonamides may also be allergic to furosemide.

What Is The Risk?

As mentioned, evidence is mixed regarding how likely someone who has a 'sulfa' allergy is to be allergic to furosemide as well.

Some studies conclude that there is essentially no risk while others warrant caution.

Overall, it appears that there is a relatively low risk of cross-sensitivity, but there certainly are at least a few published case reports that have detailed individuals who have a documented history of a sulfa allergy who were also believed to have suffered an allergic reaction to furosemide or similar 'sulfa' containing drug (that was not an antibiotic).

Having read through multiple studies on the matter, I believe an excerpt from one sums the situation up nicely:

This case and the literature review I did for it illustrate that, although cross-reactivity between sulfa antibiotics and nonantibiotics is rare, certain situations warrant prudence.

You should speak with your doctor regarding your history of allergic reactions (or your mother in this case), and discuss what the best treatment options are for the specific medical situation.

There are plenty of non-sulfa-containing diuretics available (such as amiloride, eplerenone, spironolactone, etc...) that could be options. If you, your mother, and the doctor decide that furosemide represents the best course of therapy, again, the risk of having an allergic reaction to it based on its sulfa component is low, but the individual taking the drug should nevertheless be monitored closely while taking it.

Final Words

I hope you found this answer helpful. Please reach back out anytime!