Inclusion Criteria:

1. Male or female participants aged 18 years or older.
2. Diagnosis of moderate-to-severe hidradenitis suppurativa confirmed by a dermatologist, generally corresponding to Hurley stage II or III, or active hidradenitis suppurativa considered by the investigator to require systemic treatment.
3. Presence of evaluable inflammatory lesions at baseline, allowing assessment of abscess and inflammatory nodule count, IHS4, pain NRS, pruritus NRS, and DLQI.
4. Considered by the investigator to be an appropriate candidate for treatment with upadacitinib in a real-world clinical setting.
5. Willing and able to comply with scheduled visits, laboratory testing, contraceptive requirements, and safety follow-up.
6. Able to understand the real-world and exploratory nature of the study and that upadacitinib is an investigational and off-label treatment for hidradenitis suppurativa.
7. Willing to provide written informed consent.

Exclusion Criteria:

1. A condition requiring urgent treatment, inpatient antimicrobial treatment, extensive surgery, or another emergency intervention that, in the investigator's judgment, makes participation inappropriate.
2. Active serious infection, active tuberculosis, uncontrolled chronic or recurrent infection, or another condition associated with an unacceptable risk of immunosuppression.
3. Screening results indicating hepatitis B, hepatitis C, human immunodeficiency virus infection, tuberculosis, or another infection risk that requires postponement of immunomodulatory treatment and makes participation inappropriate.
4. Clinically significant cytopenia, severe hepatic or renal impairment, or another laboratory abnormality that makes treatment with upadacitinib inappropriate.
5. Previous venous thromboembolism, a serious major adverse cardiovascular event, active malignancy, or another condition for which the investigator considers the risk of a Janus kinase inhibitor unacceptable.
6. Pregnancy, breastfeeding, or plans to become pregnant during the study.
7. A participant of childbearing potential who is unable or unwilling to use effective contraception during the study.
8. Known serious hypersensitivity or contraindication to upadacitinib or any component of the formulation.
9. Recent participation in another interventional clinical study or another condition that may interfere with the evaluation of effectiveness or safety.
10. Any unacceptable safety risk or inability to obtain key effectiveness or safety data, as determined by the investigator.