Vasodilators for Raynaud’s Phenomenon:

Calcium channel blockers


Calcium channel blockers (CCB) prevent calcium from going through calcium channels in the heart, which decreases heart rate, and the blood vessels, which causes dilation of blood vessels.  The combination of decreased heart rate and dilated blood vessels lowers blood pressure.  There are three main types of calcium channel blockers: 1.) dihydropyridines, which only dilate blood vessels; 2.) benzothiazepines, which decrease heart rate and dilate blood vessles; and 3.) phenylalkylamines, which only decrease heart rate.  Dihydropyridines (nifedipine, nicardipine, and amlodipine) are preferred for Raynaud’s phenomenon because they dilate the constricted blood vessels.

Fast facts

  • First-line drug therapy for Raynaud’s phenomenon
  • Can be used in combination with other vasodilatory drugs if needed
  • Can be used with immunosuppressive drugs
  • Important to monitor blood pressure to make sure it does not drop too low


Calcium channel blockers are used to treat high blood pressure, chest pain (angina), and abnormal heart rhythms (such as atrial fibrillation).  In addition, they are used to treat migraines, cerebral vasospasm and Raynaud’s phenomenon.

How they work

Calcium channel blockers block the contraction of vascular smooth muscle around blood vessels allowing them to relax and dilate.  They also may have an anti-platelets effect and act as antioxidants.


It is generally recommended to start at a low dose and gradually increase.  You can start with nifedipine SR 30 mg once a day and then twice a day.  The advantage of the slow release pills is that they have a longer effect.  You can start amlodipine 2.5 mg daily then increase to 5 mg and even 10 mg daily.  If you are having an acute attack of vascular spasm, then the short acting calcium channel blockers may be better.

Time to effect

Calcium channel blockers are relatively quick acting within a few days to a week.

Side effects

Calcium channel blockers may cause your blood pressure to drop, which may make you feel faint or dizzy.  They may also cause flushing or redness of the face.  Calcium channel blockers may also cause headaches, swelling of the feet, exacerbation of heart burn, constipation, gum overgrowth, nausea and constipation.  In older patients it can exacerbate eczema and dry skin.

Points to remember

Grapefruit juice may impair absorption of some calcium channel blockers and therefore should not be consumed for 2 hours before and 4 hours after taking a calcium channel blockers.  Studies have shown that calcium channel blockers reduce your Raynaud’s phenomenon attack rate and severity by one half, but not to zero.  Therefore do not be frustrated if you continue to have some attacks, although they should be less than your baseline.  In addition, you can consider rotating off in the summer months and restarting them in the winter months when your Raynaud’s phenomenon is more severe.

Drug interactions

In general, calcium channel blockers are well tolerated and can be used together with your other medications.  Calcium channel blockers should be carefully used with other medications for high blood pressure.

Information to discuss with your primary care physician and other specialists

Aside from monitoring the blood pressure, it is not necessary to do additional blood tests while you are on a calcium channel blocker.

For more information

 The Rheumatologic Dermatology Society (RDS) has compiled this list to give you a starting point for your own additional research. The RDS does not endorse or maintain these websites, and is not responsible for any information or claims provided on them. It is always best to talk with your dermatologist for more information and before making any decisions about your care.

Mayo Clinic


Advances in the treatment of Raynaud’s phenomenon