Anticoagulant Effect

• Theoretically, Pycnogenol may prevent blood platelets from sticking together, thus providing an anticoagulant effect. This can increase the risk of bleeding, particularly in people who are taking anticoagulant medication.
  
  

Immune System Considerations

• Pycnogenol is claimed to be an immune system stimulant, which could be problematic for people with autoimmune diseases such as multiple sclerosis, rheumatoid arthritis and lupus.
  
  

Blood Sugar

• Pycnogenol theroetically can lower blood sugar, thus increasing the risk of low blood sugar in people taking insulin or other diabetes medications.
  
  

Allergic Reactions

• As with any herbal supplement, Pycnogenol may cause allergic reactions in some people. Common signs of an allergic reaction include rash or hives, itching, swelling of the mouth or throat, difficulty breathing and difficulty swallowing.
  
  

Typical Side Effects

• More likely unpleasant effects associated with Pycnogenol include gastrointestinal discomfort, nausea, headaches and dizziness. Taking the herb with food can reduce the gastrointestinal effects.