This study is a multicentre, randomised, double-blind, double-dummy, phase II clinical trial with a positive-control group, designed to evaluate the efficacy and safety of dihydroartemisinin tablets in the treatment of discoid lupus erythematosus (DLE).

Participants are screened during the screening phase, and those meeting the inclusion criteria are enrolled in the study. Enrolled participants were randomised in a 2:2:1 ratio to Treatment Group 1 (dihydroartemisinin 40 mg, twice daily), Treatment Group 2 (dihydroartemisinin 60 mg, twice daily) or the control group (hydroxychloroquine 200 mg, once daily). Participants in all groups will receive treatment for 24 weeks, during which efficacy and safety will be monitored at regular intervals.

Inclusion Criteria:

1. Participants are able to understand the purpose and risks of the study and voluntarily sign an informed consent form;
2. Aged between 18 and 65 years (inclusive);
3. Body weight ≥ 45 kg;
4. Diagnosed with discoid lupus erythematosus (DLE) at the screening visit (refer to the '2021 Guidelines for the Diagnosis, Treatment and Long-term Management of Cutaneous Lupus Erythematosus'); new patients must undergo a skin biopsy and provide a pathology report, whilst existing patients must provide a biopsy pathology report dated within the last 5 years;
5. At the time of screening, the Cutaneous Lupus Erythematosus Area and Severity Index (CLASI-A) must be ≥4.

Exclusion Criteria:

1. Patients with systemic lupus erythematosus (SLE) or those at high risk of developing SLE;
2. Drug-induced lupus;
3. Patients with a history of resistance to antimalarial treatment;
4. At screening, aspartate transaminase (AST) or alanine transaminase (ALT) or gamma-glutamyltransferase (GGT) levels exceeding twice the upper limit of normal (ULN); or alkaline phosphatase (ALP) or total bilirubin levels exceeding 1.5 times the upper limit of normal (ULN); or serum creatinine (Cr) or urea (UREA) levels exceeding 1.5 times the upper limit of normal (ULN);
5. Patients diagnosed with anaemia within 3 months prior to randomisation, or patients with haemoglobin levels below 110 g/L at screening;
6. Patients who have used any antimalarial drug (hydroxychloroquine sulphate, chloroquine phosphate or chloroquine) within 4 weeks prior to randomisation;
7. Patients who have used topical corticosteroids (e.g. mometasone furoate cream or others) or topical calcineurin inhibitors (e.g. tacrolimus ointment or others) within 2 weeks prior to randomisation;
8. Patients treated with biologics (e.g. adalimumab, secukinumab or others) within 12 weeks prior to randomisation;
9. Patients treated with immunomodulators (e.g. thalidomide, lenalidomide or others) within 4 weeks prior to randomisation;
10. Patients who have received live vaccines (e.g. measles vaccine, varicella vaccine or others) within 4 weeks prior to randomisation;
11. Patients who have used traditional Chinese medicinal preparations with lupus-modulating effects within 4 weeks prior to randomisation, such as Tripterygium preparations (e.g. Tripterygium glycosides), Paeonia lactiflora total glycosides capsules, Zhengqing Fengtongning, or Euphorbia root tablets;
12. History of malignant tumours within the 5 years prior to screening;
13. History of acute myocardial infarction, unstable angina, or severe arrhythmias (multifocal frequent premature ventricular contractions, ventricular tachycardia, ventricular fibrillation) within the 6 months prior to screening, or New York Heart Association (NYHA) Class III-IV;
14. Conditions not effectively controlled at the time of screening or markedly unstable diseases (such as acute pneumonia, pulmonary arterial hypertension, diabetic ketoacidosis, acute pancreatitis, etc.), which, in the investigator's judgement, may confound the study results or expose the participant to undue risk;
15. Patients with a history of major organ transplantation (e.g., heart, lung, kidney, liver) or haematopoietic stem cell and/or bone marrow transplantation within the 5 years prior to screening;
16. A history of chronic, recurrent (three or more episodes of the same type of infection within 52 weeks) or recent severe infections (e.g. pneumonia, sepsis), including viral infections (particularly varicella and herpes zoster), or requiring anti-infective treatment during the screening period;
17. Patients who have undergone any major surgery within 6 weeks prior to randomisation, such as abdominal, thoracic or joint replacement surgery, or who are scheduled to undergo major surgery during the study (including follow-up);
18. Patients for whom the investigator, based on an ophthalmological examination prior to randomisation, considers the findings to be clinically significant and unsuitable for participation in this clinical trial, or who have diseases associated with retinal pathology;
19. Pregnant or breastfeeding women, or women of childbearing potential who do not agree to use effective contraception during the clinical trial;
20. Patients with known hypersensitivity to artemisinin-based drugs, hydroxychloroquine or excipients (lactose, microcrystalline cellulose, sodium carboxymethyl starch, sodium dodecyl sulphate, polyvinylpyrrolidone, magnesium stearate);
21. Any other circumstances, as determined by the investigator, that may interfere with the assessment of efficacy.
22. Individuals who abuse drugs or alcohol;
23. Participants who have taken part in any clinical trial within the three months prior to screening (excluding those who underwent safety checks only and did not receive any substantive medication or therapeutic.