What the FDA labels say about taking them together

Diroximel fumarate and monomethyl fumarate

Diroximel fumarate's FDA label of May 29, 2025 names monomethyl fumarate in its drug interactions section, and monomethyl fumarate's label names diroximel fumarate too. The monomethyl fumarate label: “Therefore, BAFIERTAM is contraindicated in patients currently taking dimethyl fumarate or diroximel fumarate.”

Check it at the source: the diroximel fumarate FDA label on DailyMed (effective May 29, 2025, Biogen Inc.); the monomethyl fumarate FDA label on DailyMed (effective July 16, 2026, Banner Life Sciences LLC).

What does the diroximel fumarate label say about monomethyl fumarate?

Diroximel fumarate label, drug interactions
DRUG INTERACTIONS 7.1 Concomitant Dimethyl Fumarate VUMERITY is contraindicated in patients currently taking dimethyl fumarate, which is also metabolized to monomethyl fumarate.

Source: FDA drug label (Vumerity), Biogen Inc., effective May 29, 2025 (SPL set 2d74414f-6b83-4ea2-9a95-3cecabbce774), via openFDA; the full label on DailyMed

What does the monomethyl fumarate label say about diroximel fumarate?

Monomethyl fumarate label, contraindications
CONTRAINDICATIONS BAFIERTAM is contraindicated in patients: with known hypersensitivity to monomethyl fumarate, dimethyl fumarate, diroximel fumarate, or to any of the excipients of BAFIERTAM.

Monomethyl fumarate label, drug interactions
Therefore, BAFIERTAM is contraindicated in patients currently taking dimethyl fumarate or diroximel fumarate.

Source: FDA drug label (BAFIERTAM), Banner Life Sciences LLC, effective July 16, 2026 (SPL set a161f9d4-70f1-4097-957a-eafb35d3274f), via openFDA; the full label on DailyMed

These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.

Both medicines on the record

0Diroximel fumarate generic labelers

0Monomethyl fumarate generic labelers

	Diroximel fumarate	Monomethyl fumarate
Labeled for	Multiple sclerosis	Multiple sclerosis
Boxed warning	No	No
Pharmacy cost (NADAC)	n/a	n/a
Shortage now	No current entry	No current entry

Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)

What next?

Diroximel fumarate: the full record
Monomethyl fumarate: the full record
Check more medicines together: up to five at once