Pycnogenol is generally considered safe and well tolerated. Side effects occur rarely and may include headache, dizziness, drowsiness, skin irritation, and gastrointestinal upset (e.g., nausea), the latter of which may improve if pycnogenol is taken with food.[1]
Most of the research on pycnogenol has been at least partially funded by the manufacturer of pycnogenol. While this doesn’t invalidate the research, it does make it more prone to bias in favor of pycnogenol.