Are Milk Thistle and St Johns Wort in the same botanical family?

No — Milk Thistle is Asteraceae and St Johns Wort is Hypericaceae.

Can you substitute Milk Thistle for St Johns Wort?

They come from different families (Asteraceae and Hypericaceae), so direct substitution is uncommon.

Compare · per-herb profile

Milk Thistle vs St Johns Wort

Silybum marianum · Hypericum perforatum

Milk Thistle

Silybum marianum

B Some Evidence

Family: Asteraceae
Genus: Silybum
Primary use: medicinal

Silybum marianum is a species of thistle. It has various common names including milk thistle, blessed milkthistle, Marian thistle, Mary thistle, Saint Mary's thistle, Mediterranean milk thistle, variegated thistle and Scotch thistle. This species is an annual or biennial plant of…

St Johns Wort

Hypericum perforatum

B Some Evidence

Family: Hypericaceae
Genus: Hypericum
Primary use: medicinal

Hypericum perforatum, commonly known as St. John's wort, is a flowering plant in the family Hypericaceae. It is a hairless, perennial herb with woody roots, yellow flowers marked by black glands, and leaves that appear perforated due to translucent glands, producing thousands of …

At a glance

· Different families — Asteraceae vs Hypericaceae.
· Both are primarily medicinal.
· Evidence tiers — Milk Thistle: B; St Johns Wort: B.