Pill identification — FDA label match
M 31 Pill — Allopurinol 100 mg (White, Round)
A white round tablet with the imprint M 31 matches the FDA label for Allopurinol 100 mg. Compare every detail below with your pill, and confirm with a pharmacist before relying on it.
| Imprint | M 31 |
|---|---|
| Imprint parts | M · 31 (the code is split across the pill — often one part per side) |
| Generic name | Allopurinol |
| Active ingredient(s) | Allopurinol 100 mg |
| Strength | 100 mg |
| Dosage form | Tablet |
| Colour | White |
| Shape | Round |
| Size | 10 mm |
| Score | Two even pieces |
| Labeler | Remedyrepack Inc. |
| NDC examples | 70518-4412-0, 52125-309-02 |
What this medicine is
According to its FDA-approved label, Allopurinol is described as follows (reference information only — not advice about whether it is right for anyone):
Allopurinol tablets are indicated for: The management of adults with signs and symptoms of primary or secondary gout (acute attacks, tophi, joint destruction, uric acid lithiasis, and/or nephropathy) The management of adult and pediatric patients with leukemia, lymphoma and solid tumor malignancies...
Equivalent pills — same medicine, different imprint
The pills below contain the same active ingredient at the same strength (Allopurinol 100 mg). Different makers stamp their own codes, so equivalent pills often look completely different. This is factual label information — it is not a suggestion to substitute one product for another; only a pharmacist or prescriber can advise on that.
Frequently asked questions
What pill has the imprint M 31?
A white round tablet with the imprint M 31 matches the FDA label for Allopurinol 100 mg. Always compare the colour, shape and size as well — short imprints are shared by different medicines — and confirm with a pharmacist.
What does the M 31 pill look like?
On its FDA label it is described as a white round tablet, 10 mm, with a score recorded as: two even pieces.
How can I be sure this identification is right?
Check every characteristic — imprint (both sides), colour, shape, size and score — against the pill in your hand. If all of them agree, the pill matches the FDA label shown here, but that is still not a guarantee: counterfeit pills copy real imprints. A pharmacist can confirm the identification in person, and you should never take a pill you are not certain about.
Browse: all pills with imprint M 31 · Allopurinol — all forms & strengths · White pills · Round pills
Source: FDA label data via DailyMed/openFDA · Label set ID 8f50e91e-66a7-4fd4-888a-9f1986aa661c · Record extracted from the openFDA bulk export of October 29, 2026. Spotted an error? Report it — include the imprint and what looks wrong.