Organization	6 Months Ended
Jun. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Description of Business Exagen Inc. (the Company) is a medical technology company primarily focused on the design, development and commercialization of a next-generation portfolio of testing products under the AVISE® brand, which allow for the differential diagnosis, prognosis and monitoring of complex rheumatic, autoimmune and autoimmune-related disease including, among others, systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Liquidity The Company has incurred recurring losses and negative cash flows from operating activities since inception. The Company anticipates that it will continue to incur net losses in future periods. As of June 30, 2025, the Company had cash and cash equivalents of $30.0 million and had an accumulated deficit of $302.5 million. Since inception, the Company has financed its operations primarily through a combination of equity financings, debt financing arrangements, and revenue from sales of the Company's products. Based on the Company's current business plan, management believes that its existing capital resources will be sufficient to fund the Company's obligations for at least twelve months following the issuance of these condensed financial statements. On April 25, 2025, the Company and Perceptive Credit Holdings IV, LP (Perceptive) entered into the Credit Agreement (as defined below), under which an initial term loan of $25.0 million was funded, $19.7 million of which the Company used to repay the 2017 Term Loan (as defined below). The Company received $3.0 million in proceeds, net of issuance costs and repayment of the 2017 Term Loan. The term loan facility allows the Company to draw up to an aggregate principal amount of $75.0 million in several tranches, subject to specified milestone requirements. Additionally, pursuant to the Credit Agreement, the Company also issued a warrant certificate to purchase up to 1,150,000 shares of common stock (the Warrant Certificate), 400,000 of which vested and became exercisable upon issuance (the Tranche A Warrant Shares) and up to 750,000 of which will vest and become exercisable if and when the additional debt tranches are drawn by the Company. See “Note 4 Borrowings—Perceptive Term Loan Facility” for more information. On May 9, 2025, the Company issued and sold an aggregate of 3,852,500 shares of its common stock at a public offering price of $5.25 per share, for aggregate net proceeds of $18.6 million after deducting underwriting discounts and commissions and other offering expenses. See “Note 7 Stockholders' Equity—2025 Public Offering” for more information. To execute its business plans, the Company may need additional funding to support its continuing operations and pursue its growth strategy. Until such time as the Company can achieve significant cash flows from operations, if ever, it may need to finance its operations through the sale of its stock, debt financings or other strategic transactions. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing on terms acceptable to the Company, if at all. The terms of any financing may adversely affect the holdings or the rights of the Company's stockholders. Although management believes the Company's existing capital resources are adequate to fund operations for the next twelve months, if the Company is unable to obtain additional funding in the future, the Company could be forced to delay, reduce or eliminate some or all of its programs, product portfolio expansion plans or commercialization efforts, which could have a material adverse effect on the Company's business, operating results and financial condition and the Company's ability to achieve its intended business objectives.

Exagen Inc. (the Company) is a medical technology company primarily focused on the design, development and commercialization of a next-generation portfolio of testing products under the AVISE® brand, which allow for the differential diagnosis, prognosis and monitoring of complex rheumatic, autoimmune and autoimmune-related disease including, among others, systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

The Company has incurred recurring losses and negative cash flows from operating activities since inception. The Company anticipates that it will continue to incur net losses in future periods. As of June 30, 2025, the Company had cash and cash equivalents of $30.0 million and had an accumulated deficit of $302.5 million. Since inception, the Company has financed its operations primarily through a combination of equity financings, debt financing arrangements, and revenue from sales of the Company's products. Based on the Company's current business plan, management believes that its existing capital resources will be sufficient to fund the Company's obligations for at least twelve months following the issuance of these condensed financial statements.

On April 25, 2025, the Company and Perceptive Credit Holdings IV, LP (Perceptive) entered into the Credit Agreement (as defined below), under which an initial term loan of $25.0 million was funded, $19.7 million of which the Company used to repay the 2017 Term Loan (as defined below). The Company received $3.0 million in proceeds, net of issuance costs and repayment of the 2017 Term Loan. The term loan facility allows the Company to draw up to an aggregate principal amount of $75.0 million in several tranches, subject to specified milestone requirements. Additionally, pursuant to the Credit Agreement, the Company also issued a warrant certificate to purchase up to 1,150,000 shares of common stock (the Warrant Certificate), 400,000 of which vested and became exercisable upon issuance (the Tranche A Warrant Shares) and up to 750,000 of which will vest and become exercisable if and when the additional debt tranches are drawn by the Company. See “Note 4 Borrowings—Perceptive Term Loan Facility” for more information.

On May 9, 2025, the Company issued and sold an aggregate of 3,852,500 shares of its common stock at a public offering price of $5.25 per share, for aggregate net proceeds of $18.6 million after deducting underwriting discounts and commissions and other offering expenses. See “Note 7 Stockholders' Equity—2025 Public Offering” for more information.

To execute its business plans, the Company may need additional funding to support its continuing operations and pursue its growth strategy. Until such time as the Company can achieve significant cash flows from operations, if ever, it may need to finance its operations through the sale of its stock, debt financings or other strategic transactions. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing on terms acceptable to the Company, if at all. The terms of any financing may adversely affect the holdings or the rights of the Company's stockholders. Although management believes the Company's existing capital resources are adequate to fund operations for the next twelve months, if the Company is unable to obtain additional funding in the future, the Company could be forced to delay, reduce or eliminate some or all of its programs, product portfolio expansion plans or commercialization efforts, which could have a material adverse effect on the Company's business, operating results and financial condition and the Company's ability to achieve its intended business objectives.