From the Guidelines
Verapamil is not considered a teratogen and can be used during pregnancy when the benefits outweigh the potential risks. According to the most recent and highest quality study available, which is from 2025 1, the focus is on the management of hypertension in pregnancy and postpartum, and while verapamil is not listed as a first-line agent for postpartum hypertension, its use during pregnancy is not contraindicated. The study from 2015 1 also supports the use of verapamil during pregnancy, categorizing it as a class C drug, meaning that the potential benefits outweigh the risks. The 2011 study 1 provides further evidence that verapamil is well-tolerated during pregnancy, with limited experience but no clear association with congenital malformations.
Key points to consider when using verapamil during pregnancy include:
- It is classified as FDA pregnancy category C, indicating that animal studies have shown adverse effects, but there are no adequate well-controlled studies in humans.
- Clinical experience has not demonstrated a clear association with congenital malformations.
- If verapamil is needed, it should be used at the lowest effective dose and under close medical supervision.
- Other agents like methyldopa or labetalol may be preferred as first-line options for treating hypertension during pregnancy due to more extensive safety data.
The mechanism of action of verapamil, blocking calcium channels in vascular smooth muscle and cardiac cells, reduces blood pressure and heart rate without directly affecting fetal development pathways. Therefore, verapamil can be a viable option for managing certain conditions during pregnancy, under the guidance of a healthcare provider.
From the FDA Drug Label
Reproduction studies have been performed in rabbits and rats at oral doses up to 1. 5 (15 mg/kg/day) and 6 (60 mg/kg/day) times the human oral daily dose, respectively, and have revealed no evidence of teratogenicity.
Verapamil is not teratogenic according to the reproduction studies in rabbits and rats, as there was no evidence of teratogenicity found at doses up to 1.5 and 6 times the human oral daily dose, respectively 2.
From the Research
Verapamil Teratogenicity
- There is limited direct evidence on the teratogenic effects of verapamil, a calcium channel blocker, in humans 3, 4, 5.
- A study on chick embryos found that verapamil potentiated the cardiovascular teratogenicity of phenobarbital, suggesting a potential teratogenic effect 4.
- However, another study on gravid ewes found that verapamil did not have a significant effect on fetal hemodynamics, suggesting that it may be safe for use in pregnancy 3.
- A review of calcium channel blockers, including verapamil, found that they have little teratogenic or fetotoxic potential, but this review primarily focused on nifedipine 6.
- A population-based study on teratogenic medication exposures during pregnancy did not specifically mention verapamil as a medication with known or potential teratogenic risk 7.
Medication Safety in Pregnancy
- The safety of verapamil in pregnancy is not well established, and more research is needed to fully understand its potential teratogenic effects 3, 4, 5.
- Other calcium channel blockers, such as nifedipine, have been found to be safe and effective for use in pregnancy, but the safety of verapamil specifically is unclear 6.
- The use of verapamil in postpartum hypertension has been studied, and it appears to be effective in reducing blood pressure, but its safety in this context is not well established 5.