From the Research
Most antihistamines are considered safe for patients with Glucose-6-phosphate dehydrogenase (G6PD) deficiency. Second-generation antihistamines like cetirizine (10mg daily), loratadine (10mg daily), fexofenadine (180mg daily), and desloratadine (5mg daily) are generally preferred due to their minimal side effects and lack of known interactions with G6PD pathways 1. First-generation antihistamines such as diphenhydramine (25-50mg every 4-6 hours) and chlorpheniramine (4mg every 4-6 hours) are also considered safe, though they may cause more sedation and anticholinergic effects.
The safety of antihistamines in G6PD deficiency stems from their mechanism of action, which involves blocking histamine receptors rather than interfering with the pentose phosphate pathway affected in G6PD deficiency. Unlike certain medications (such as primaquine, dapsone, and some sulfa drugs) that can trigger hemolytic anemia in G6PD-deficient individuals by increasing oxidative stress, antihistamines do not generate reactive oxygen species that would require G6PD for detoxification 2. However, as individual responses can vary, it's always prudent to monitor for any unusual symptoms when starting any new medication in patients with G6PD deficiency.
Some key points to consider when prescribing antihistamines to patients with G6PD deficiency include:
- Monitoring for signs of hemolysis, such as jaundice or dark urine
- Avoiding medications that are known to trigger hemolytic anemia in G6PD-deficient individuals
- Choosing antihistamines with minimal side effects and lack of known interactions with G6PD pathways
- Considering the use of second-generation antihistamines as first-line treatment due to their favorable safety profile 3.
Overall, the use of antihistamines in patients with G6PD deficiency is generally considered safe, but it's essential to exercise caution and monitor for any potential adverse effects.