Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the following Registration Statements:

1. Registration Statement (Form S-8, File No. 333-221306) pertaining to the 2011 Stock Incentive Plan, the 2017 Stock Option and Incentive Plan, and the 2017 Employee Stock Purchase Plan of Allena Pharmaceuticals, Inc.,

2. Registration Statement (Form S-8, File No. 333-223939) pertaining to the 2017 Stock Option and Incentive Plan and the 2017 Employee Stock Purchase Plan of Allena Pharmaceuticals, Inc., and

3. Registration Statement (Form S-3, File No. 333-228656) and related Prospectus of Allena Pharmaceuticals, Inc. for the registration of common stock, preferred stock, debt securities, warrants, and units;

of our report dated March 7, 2019, with respect to the consolidated financial statements of Allena Pharmaceuticals, Inc., included in this Annual Report (Form 10-K) for the year ended December 31, 2018.

/s/ Ernst & Young LLP

Boston, Massachusetts

March 7, 2019