The main two disorders where verapamil is used are migraine and meniere's disease -- two closely related "committee" diagnoses. In other words, these two disorders overlap heavily, are diagnosed using entirely subjective criteria, and could even be often two faces of the same illness.
The usual dose of verapamil is 120 to 240 mg, SR, once per day. SR means sustained release. This drug is an dihydropyridine L-channel calcium channel blocker, similar to other dihydropyridine drugs like nifedipine, nimodipine and diltiazem.
Verapamil is modestly effective for migraine but it takes about 2 weeks to work, and dose may need to be escalated too requiring more time. According to Davidoff (2002), doses as high as 480 mg/day may be necessary for migraine. Verapamil is effective in migraine variants such as hemiplegic migraine (Yu and Horowitz, 2003; Davidoff 2002), perhaps because of the pathophysiology of hemiplegic migraine that can involve the calcium channel receptor. Compared to beta-blockers, verapamil is less effective for common migraine (Davidoff, 2002).
Verapamil also may be helpful in Menieres disease, although this has not yet been documented by a controlled study. A close relative to verapamil, Nimodipine has been reported to be helpful for Meniere's disease (Lassen et al, 1996). Neither of these medications are used commonly in Meniere's. Meniere's disease is plagued by reports of treatments that are initially thought to be helpful, but later inseparable from placebo. This is due the extreme variability and relative infrequency Meniere's, making it easy to be fooled. See this link for more. Meniere's and migraine are close relatives. In fact, about 50% of patients with Meniere's, also have Migraine (Radke et al, 2002; Rassekh et al, 1992). It doesn't work the other way around however. This may be the reason why prevention treatment of Meniere's and migraine, including various diets and medications, overlap extensively.
About 50% of users of verapamil develop mild constipation. We like to combine verapamil prescriptions with oral magnesium supplements (500 mg/day), as magnesium has some tendency to counteract the constipation and is also a prevention medication for migraine. (Holland, 2012)
Sometimes verapamil lowers blood pressure but this is generally not a big problem if it is started gradually. About 1% of users develop palpitations (fluttering feeling in chest). Stop taking this drug if you develop palpitations. A few individuals develop swelling of the ankles. Verapamil is safe in patients with asthma, and especially good in patients who also have high blood pressure. Should start with dose mg. roughly = weight of patient (in pounds).
Verapamil has no cognitive side effects and no effect on weight. Some studies even reported that calcium channel blockers enhance cognition (Kowalska and Disterhoft, 1994). However, this observation has not stood the test of time.
There are several concerns about verapamil that should limit its use. Because of studies suggesting increased mortality from heart disease, verapamil and related drugs in the calcium channel blocker family are not favored in individuals aged 55 and older.
Verapamil is one of the drugs favored for treatment of cluster headache in pregnancy and lactation (Jurgens et al, 2009).
One study suggested an increased risk of cancer (about 2 fold) in persons taking verapamil in Rotterdam (Biederbeck-Noll et al, 2003). However, the study of Dong et al (1997) included 11,000 patients in all published trials at the time and found "There is no statistically significant increased risk of cancer or deaths with verapamil compared with active controls or placebo." We think the much larger and more geographically diverse study of Dong is more likely to be correct than a smaller study done in a single country. As verapamil is often associated with constipation, and constipation increases the risk of colon cancer, one could speculate that verapamil might increase the risk of colon cancer. However, if one keeps the constipation under control with diet or appropriate laxatives, this risk should be nonexistent.
Verapamil increases blood levels of simvistatin (Kantola et al, 1998). Doses of simvistatin should be reduced to 10mg when verapamil is also prescribed. Statins also increase the bioavailability of verapamil (Choi et al, 2010), and when a statin and verapamil are combined, doses of verapamil should also be decreased.