From the Guidelines
Hydrochlorothiazide (HCTZ) is a sulfa drug, but it is a non-antimicrobial sulfonamide, which has a low risk of cross-reactivity with sulfonamide antimicrobials.
Key Points
- HCTZ is classified as a thiazide diuretic, which is a type of non-antimicrobial sulfonamide 1.
- Non-antimicrobial sulfonamides, such as HCTZ, have a low risk of cross-reactivity with sulfonamide antimicrobials due to their different chemical structure 1.
- The risk of cross-reactivity is minimal, and HCTZ can be used in patients with a history of sulfonamide antimicrobial adverse reactions, unless they have a specific allergy to HCTZ itself 1.
- Some studies suggest that patients with a history of sulfonamide allergy can tolerate HCTZ, but caution is still advised 1.
Evidence
- A 2022 practice parameter update on drug allergy states that HCTZ is a non-antimicrobial sulfonamide with no or weak evidence of cross-reactivity in patients with a history of sulfonamide antimicrobial adverse reactions 1.
- A study on guidelines for using antiretroviral agents among HIV-infected adults and adolescents mentions that amprenavir, a sulfonamide, should be used with caution in patients with a history of sulfa allergies, but does not provide information on HCTZ specifically 1.
- Other studies on treating opportunistic infections and resistance testing of meningococci do not provide relevant information on HCTZ or its cross-reactivity with sulfonamide antimicrobials 1.
- A 2021 review on adverse effects of medications on micronutrient status discusses the effects of thiazide diuretics, including HCTZ, on bone health, but does not address the issue of cross-reactivity with sulfonamide antimicrobials 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 and Classification of Hydrochlorothiazide
- Hydrochlorothiazide (HCTZ) is a sulfonamide-containing drug, as stated in the study published in 2009 3.
- It belongs to the class of diuretic agents, specifically a thiazide-type diuretic, as mentioned in the study published in 2018 4 and 2016 5.
- HCTZ is used in the treatment of hypertensive patients, as noted in the studies published in 2009 3, 2016 5, and 2015 6.
Relationship between HCTZ and Sulfa Drugs
- HCTZ contains a sulfonamide group, which is also present in sulfa antibiotics, as mentioned in the studies published in 2009 3 and 2006 7.
- However, the mechanism of allergic reactions to HCTZ is unlikely to be cross-sensitivity between sulfonamide antibiotics and sulfonamide nonantibiotic drugs, as stated in the study published in 2009 3.
- There have been reports of patients with a history of hypersensitivity reactions to sulfonamide antibiotics experiencing allergic-like reactions to HCTZ, as described in the studies published in 2006 7 and 2015 6.
Adverse Reactions and Side Effects
- HCTZ has been associated with various adverse effects, including electrolyte abnormalities, orthostatic hypotension, hyperglycemia, and photosensitivity, as mentioned in the study published in 2009 3.
- Rare but serious drug complications, such as interstitial pneumonitis, angioedema, and aplastic anemia, have also been reported, as stated in the study published in 2009 3.
- Other reported side effects include acute respiratory distress syndrome, as described in the study published in 2018 4, and myopericarditis, as reported in the study published in 2015 6.