Function

• Dynacirc CR decreases the rate at which calcium enters the heart and blood vessel walls. This relaxes and widens the vessels, improving blood flow.
  
  

Edema

• In clinical trials with Dynacirc CR, as detailed by eMedTV, fluid retention causing swelling (edema) was the most common side effect. This was experienced by nearly 36 percent of participants in some studies. Dynacirc CR is commonly prescribed with a diuretic to prevent this side effect.
  
  

Common Side Effects

• Other side effects associated with Dynacirc CR include abdominal pain, upset stomach, constipation, facial flushing, fatigue and headaches. These effects typically clear up within a few weeks.
  
  

Low Blood Pressure

• Dynacirc CR can cause a steep drop in blood pressure, leading to dizziness, lightheadededness or even fainting. This is most common early in treatment when getting up from sitting or lying down.
  
  

Serious Side Effects

• Some people have a rare allergic reaction to Dynacirc CR, with rash or hives, difficulty breathing, and facial or mouth swelling. Other serious side effects include chest pain, rapid or irregular heartbeat, skin numbness or tingling, confusion, speech problems and severe headache.
  
  

Drug Interactions

• Dynacirc CR interacts with numerous other drugs. These include certain antibiotics, anti-fungal drugs, protease inhibitors, cimetadine, delavirdine, fentanyl and nefazodone.