Pharmacovigilance profile
An antimalarial that became a cornerstone for lupus and rheumatoid arthritis — and a drug whose eyes-and-heart safety story deserves a careful read. Here is what it treats, where it is used off-label, and what the safety reports show.
Drug profile
Hydroxychloroquine accumulates in acidic intracellular compartments, raises their pH and modifies immune signalling — interfering with lysosomal activity, antigen processing and toll-like receptor signalling. That calms inflammatory activity in autoimmune disease.
Its antimalarial action comes from interfering with the parasite's digestion of haemoglobin.
Indications vs off-label
The 17 example conditions in this dossier. Conceptual split — not market share or prescribing frequency.
Systemic lupus erythematosus
Controls disease activity and reduces flares
Chronic discoid lupus
Controls skin manifestations
Rheumatoid arthritis
Reduces joint inflammation and disease activity
Uncomplicated malaria
Treats susceptible malaria parasites
Malaria prophylaxis
Prevention where chloroquine resistance is absent
Not appropriate for chloroquine-resistant or complicated malaria.
Qualitative summaries, not formal GRADE assessments. COVID-19 is not a recommended use — treatment or prevention — given the lack of demonstrated benefit and the safety concerns.
Adverse drug reactions
Distinct serious reactions listed in the dossier, grouped by system. A count of ADR types — not patient frequencies.
Cardiac toxicity leads the list — QT prolongation, cardiomyopathy and torsades de pointes can all have serious consequences.
Retinal toxicity matters most in long-term use, because the damage can be irreversible.
EudraVigilance · 2019 vs 2020
| 2019 → 2020 volume | ||||
|---|---|---|---|---|
| ECG QT prolongedCardiac | 1 | 400 | +399 ×400 | |
| Hepatic enzyme increasedLiver | 56 | 256 | +200 ×4.6 | |
| Visual impairmentEye | 55 | 96 | +41 ×1.7 | |
| Retinal toxicityEye | 7 | 92 | +85 ×13 | |
| Cardiac failureCardiac | 2 | 41 | +39 ×21 | |
| Long QT syndromeCardiac | 0 | 38 | +38 new | |
| Cardiac arrestCardiac | 2 | 35 | +33 ×18 | |
| Total of shown events | 123 | 958 | 2020 2019 | ×7.8 |
Raw spontaneous-report counts from a published EudraVigilance descriptive analysis. Reporting patterns only — not incidence rates, and not proof that hydroxychloroquine caused each event.
Safety monitoring
Retinal-safety dose ceiling
An illustration of the AAO 2025 screening threshold only — not a prescribing tool. Dosing is decided by the treating clinician.
Ophthalmological exam
Detect retinal toxicity — Baseline (OCT + FAF), then annual screening
ECG
Identify QT prolongation — Patients with cardiac risk factors
Renal function
Impaired drug clearance — Periodic assessment
Liver function
Possible liver injury — As clinically indicated
Complete blood count
Haematological abnormalities — As clinically indicated
Blood glucose
Detect hypoglycaemia — Where clinically appropriate