Company: INTS
Filing Date: 2025-06-12
Form Type: 424B5
Source: 0001628280-25-031040
Chunk: 2

Company: INTENSITY THERAPEUTICS, INC.
Filing Date: 2025-06-12
Form: 424B5
Chunk 2
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 You Can Find Additional Information         |     | S-30 |
| Incorporation of Certain Information By Reference |     | S-31 |

| Prospectus                                         |     | Page |
| About This Prospectus                              |     |    1 |
| About Intensity                                    |     |    2 |
| Risk Factors                                       |     |    5 |
| Special Note Regarding Forward-Looking Information |     |    6 |
| Use Of Proceeds                                    |     |    8 |
| The Securities We May Offer                        |     |    9 |
| Description Of Capital Stock                       |     |   10 |
| Description Of Debt Securities                     |     |   14 |
| Description Of Warrants                            |     |   23 |
| Description Of Units                               |     |   25 |
| Plan Of Distribution                               |     |   26 |
| Legal Matters                                      |     |   30 |
| Experts                                            |     |   30 |
| Where You Can Find More Information                |     |   30 |
| Incorporation Of Certain Documents By Reference    |     |   30 |

<div align='center'>S-i</div>

### ABOUT THIS PROSPECTUS SUPPLEMENT
This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of securities and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus dated July 11, 2024, including the documents incorporated by reference therein, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or in any document incorporated by reference that was filed with the Securities and Exchange Commission, or the SEC, before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date-for example, a document incorporated by reference in the accompanying prospectus-the statement in the document having the later date modifies or supersedes the earlier statement.

This prospectus supplement is part of a registration statement that we filed with the SEC using a “shelf” registration process. Under the