Common (>10% users):

• Mild GI upset (nausea, soft stools) — usually if taken without food. Eliminated by taking with breakfast.
• None considered clinically meaningful at 100-200 mg/day.

Less common (1-10%):

• Headache — rare, usually at >300 mg/day.
• Dizziness — rare, possibly via mild vasodilation in BP-sensitive users.
• Mouth ulcers / oral discomfort — rare, idiosyncratic.

Rare-serious (<1%):

• Allergic reaction — skin rash, pruritus, urticaria, very rarely anaphylaxis. People with pine pollen allergy, conifer allergy, or general polyphenol/flavonoid hypersensitivity should be cautious. Cross-reactivity with grape seed extract reported. Discontinue if rash develops.
• Theoretical bleeding risk with anticoagulants — mild antiplatelet effect (TXB2 reduction). Case reports of INR elevation in warfarin patients on >200 mg/day Pycnogenol. Worth flagging at high doses with anticoagulation; not relevant to the user.
• Theoretical hypotension at high doses with antihypertensives — Pycnogenol's mild BP-lowering effect (~3-4 mmHg systolic in hypertensive populations) could compound prescription antihypertensives. Not relevant to the user.
• Pregnancy / lactation — safety data thin. Manufacturer recommends defer in pregnancy and breastfeeding. Not relevant to the user; flag for partner.
• Autoimmune flare (theoretical) — Pycnogenol modulates immune function (mostly anti-inflammatory, but some immune activation in lupus / SLE trials). Patients with active autoimmune disease should consult prescriber.

Specific watch periods:

• First 4 weeks: monitor for GI tolerance, allergic skin reactions, headache.
• 6 months / annually: routine ALT/AST (no DILI signal documented but standard supplement vigilance).