From the Guidelines
No, Hydrochlorothiazide (HCTZ) is not considered a sulfa drug in the context of cross-reactivity with sulfonamide antimicrobials 1.
Key Points
- HCTZ is a thiazide diuretic that is structurally different from sulfonamide antimicrobials 1.
- According to the 2022 practice parameter update, there is minimal concern for cross-reactivity between sulfonamide non-antimicrobials, including HCTZ, and sulfonamide antibiotics 1.
- The study lists HCTZ as a drug with no or weak evidence of cross-reactivity in patients with a history of a sulfonamide antimicrobial adverse reaction 1.
Implications
- Patients with a history of sulfonamide antimicrobial allergy can likely tolerate HCTZ without an increased risk of cross-reactivity 1.
- This information is important for clinicians to consider when prescribing medications to patients with a history of sulfa allergy, as it may help to expand treatment options 1.
From the FDA Drug Label
WARNINGS Acute Myopia and Secondary Angle-Closure Glaucoma: Hydrochlorothiazide, a sulfonamide, can cause an idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma. CONTRAINDICATIONS Hydrochlorothiazide capsules are contraindicated in patients with anuria. Hypersensitivity to this product or other sulfonamide derived drugs is also contraindicated.
Yes, Hydrochlorothiazide (HCTZ) is a sulfa drug, as it is a sulfonamide derivative 2 and 2.
From the Research
Definition of a Sulfa Drug
A sulfa drug is a type of medication that contains a sulfonamide group, which is a specific chemical structure.
Classification of Hydrochlorothiazide (HCTZ)
- HCTZ is classified as a sulfonamide-containing drug 3, 4, 5, 6
- It is a thiazide-type diuretic medication, commonly prescribed for hypertension 3, 5
- HCTZ belongs to the class of diuretic agents, which are prohibited in sports according to the World Anti-Doping Agency (WADA) regulations 7
Relationship Between HCTZ and Sulfa Allergy
- There have been reports of hypersensitivity reactions to HCTZ in patients with a history of sulfonamide allergy 3, 4
- However, the mechanism of the allergic reaction to HCTZ is not clear, and evidence suggests that it may be due to a predisposition to drug allergies rather than sulfonamide cross-sensitivity 3
- Clinicians should be aware of the potential for allergic reactions to HCTZ in patients with a history of sulfonamide allergy, and monitor them closely when receiving these drugs 3, 4