GLA (Evening Primrose Oil)

Supplements · Fatty Acids · Supplement, Typed Supps

A plant oil people try for skin and period-related discomfort — though good evidence for either is thin.

Stage by stage

Intake (Softgel): Digested like dietary fat, requiring bile for emulsification.
Small intestine (Fat-processing pathway): Absorbed via the same route as other fat-soluble compounds.
Bloodstream (Incorporated into cell membranes): Carried through the blood and incorporated into cell membranes throughout the body.
Skin & inflammatory signalling (Studied effects): Studied for effects on skin barrier function and, separately, premenstrual discomfort.

What the evidence supports

Improving atopic eczema — insufficient evidence. A Cochrane review of oral evening primrose oil found no clinically meaningful benefit for eczema versus placebo — a documented negative for one of its most popular uses.
Relieving cyclical breast pain (mastalgia) — limited evidence. Evidence is mixed; several trials and reviews found it no better than placebo, though some suggest modest relief in selected people.
Easing menopausal or premenstrual symptoms — limited evidence. Small trials are inconsistent and generally low quality; benefit is not reliably shown.

Typical dose

Commonly around 1–3 g/day of evening primrose oil (roughly 8–10% GLA)

Upper limit: No established UL

Timing

With a fat-containing meal.

Time to effect

Wks–mo: Any reported skin or symptom effect in studies.

Medication interactions

Anticoagulants and antiplatelets: May add to a modest bleeding-risk effect. (moderate)
Phenothiazines and drugs that lower the seizure threshold: Case reports suggest a possible increased seizure risk; caution is advised (per NCCIH). (moderate)

Common myth

“Evening primrose oil is strongly evidenced for eczema.” In reality: More recent, larger trials have generally been less impressive than earlier smaller studies suggested.