Plaquenil (Hydroxychloroquine): Uses, Dosage, Side Effects, and Safety in 2025

You’re here because you’ve heard of Plaquenil and want the no-nonsense version: what it treats, how to take it right, what risks are real (and which ones are overblown), and how to stay safe. Here’s the short of it: hydroxychloroquine (the generic name) is a steady, slow-burn medicine that helps calm autoimmune diseases like rheumatoid arthritis and lupus. The big worry is eye damage, but at the right dose and with routine eye checks, the risk stays low. It doesn’t work overnight, it doesn’t replace steroids on day one, and it definitely isn’t used for COVID-19 anymore. Expect straight talk, practical steps, and the key numbers you can use to make good calls with your doctor.

TL;DR and quick facts

Key takeaways

• What it is: Hydroxychloroquine (brand: Plaquenil) is a disease-modifying drug for autoimmune conditions (rheumatoid arthritis, lupus). It also has old-school malaria uses, but that’s not common in 2025.
• When it helps: Eases joint pain, skin rashes, fatigue, and helps prevent lupus flares. It doesn’t blunt pain instantly; benefits build over 6-12 weeks.
• Dose rule: Keep daily dose at or below 5 mg/kg of your actual body weight (most adults: 200-400 mg/day). This is the main lever to cut eye risk.
• Safety: The eye risk (retinopathy) is low at proper doses and monitoring. Baseline eye exam within the first year, then yearly after 5 years-or earlier if high risk.
• What changed: No role for COVID-19 treatment or prevention (per WHO/NIH). Pregnancy: usually continued for lupus/RA; widely considered compatible with breastfeeding (per ACR/EULAR).

Who this guide is for: If you’ve just been prescribed hydroxychloroquine, you’ve taken it for years and want a safety check, or you’re weighing risks vs. benefits with your rheumatology or dermatology team, this is for you. The examples reflect 2025 practice, with notes for New Zealand readers where it matters.

Why you can trust these numbers: The dosing and eye-risk guidance track the American Academy of Ophthalmology recommendations (updated from the 2016 guideline), and rheumatology practice patterns align with ACR/EULAR guidance. COVID-19 stance mirrors WHO/NIH positions (no indication). NZ availability reflects Medsafe advisories and routine pharmacy practice as of 2025.

How to use hydroxychloroquine safely (dosing, monitoring, interactions)

Job #1: Know if it’s right for you

• Best fit: Rheumatoid arthritis, systemic lupus erythematosus (SLE), cutaneous lupus, and some other autoimmune skin/joint conditions. It’s often a background medicine that lowers disease activity and steroid needs.
• Not for: COVID-19 treatment/prevention; it’s not effective for that, and guidelines moved on years ago.
• Sometimes: Sjögren’s symptoms, sarcoidosis skin disease, porphyria cutanea tarda-these are specialist calls.

Job #2: Nail the dose

1. Do the weight check: Keep total daily dose ≤5 mg/kg of your actual body weight. Example: if you weigh 70 kg, target ≤350 mg/day-so 200-300 mg/day is ideal, 400 mg/day is acceptable if benefits outweigh risks and you’re monitored.
2. Common starting plan: 200 mg once daily for 1-2 weeks, then up to 200 mg twice daily if needed and safe for your weight.
3. With food: Take it with a meal to cut nausea. If reflux or tummy upset hits, split the dose (e.g., morning and evening).
4. Missed dose? Take it when you remember unless it’s close to your next dose. Don’t double up.
5. How long before it helps: Give it 6-12 weeks for a fair trial. Many doctors reassess at 3 months, then adjust the plan at 6 months if needed.

Job #3: Get the monitoring right

• Eye screening: Book a baseline comprehensive eye exam within the first year of use. After 5 years, get yearly screening. Go earlier and yearly right away if you’re high risk (dose above 5 mg/kg/day, kidney disease, tamoxifen use, or pre-existing macular disease).
• What eye tests look like: Visual fields and optical coherence tomography (OCT) are the workhorses. These can spot changes well before you notice symptoms.
• Kidney/liver checks: Baseline bloods (kidney function, sometimes liver) help set a reference. If you have kidney disease, your doctor may lower the dose and screen eyes sooner.
• Blood counts: Not routinely needed like with some other DMARDs. Your clinician might still track labs if you’ve got other conditions or medicines.
• When to call fast: New vision symptoms (trouble reading, missing spots in your vision, changes in color vision), fainting, palpitations, or severe low blood sugar symptoms (shakiness, sweating, confusion).

Job #4: Avoid interactions and pitfalls

• QT-prolonging drugs: Combining hydroxychloroquine with other QT-prolongers (like azithromycin, some antiarrhythmics such as amiodarone or sotalol, some antipsychotics, certain antidepressants) can raise rhythm risk. If you’re on any of these, your prescriber may check an ECG or choose another plan.
• Digoxin: Levels can go up. If you take digoxin, you may need closer level checks.
• Antacids and kaolin: Space hydroxychloroquine at least 4 hours apart to avoid reduced absorption.
• Cimetidine: Can raise hydroxychloroquine levels. Many clinicians prefer other reflux meds if needed.
• Blood sugar meds: Hydroxychloroquine can enhance insulin and sulfonylurea effects; watch for hypoglycemia, especially when starting or changing doses.
• Tamoxifen: Raises retinal toxicity risk; eye screening needs to be tighter.

Safety habits that pay off

• Stick to the 5 mg/kg/day rule. Dose is the single biggest modifiable risk factor for the eyes.
• Take with food. Most tummy issues fade in a couple of weeks when you do this.
• Track your weight yearly and recalc your dose if your weight changes a lot.
• Keep a meds list on your phone, including over-the-counter and supplements. Show it at every appointment.
• In NZ, medicines and brand supply can shift. If your tablet looks different, confirm it’s still hydroxychloroquine 200 mg with your pharmacist.

What about alcohol, sunlight, travel?

• Alcohol: No specific ban, but keep it moderate, especially if you’ve got liver issues or take methotrexate too.
• Sun: Photosensitivity can happen. Use sunscreen and a hat-especially under that sharp New Zealand sun.
• Travel: If you’re heading to malaria regions, ask a travel clinic. Hydroxychloroquine has limited roles now due to resistance; other prophylaxis options are usually preferred.

Side effects, scenarios, and your action plan (FAQs + checklists)

Common side effects (usually mild, often improve)

• Nausea, stomach cramps, diarrhea or constipation
• Headache, dizziness
• Rash or itch; skin may get darker or lighter in patches
• Sleep changes or vivid dreams

Serious side effects (rare-know the red flags)

• Eye changes: Trouble reading, crooked lines, blind spots, color changes, or trouble seeing in dim light. Call your doctor; don’t wait for your next routine eye check.
• Heart rhythm problems: Fainting, rapid or irregular heartbeat-especially if you’re on other QT-prolonging drugs.
• Severe hypoglycemia: Sweating, shaking, confusion, blurry vision-treat it like a low and contact your clinician.
• Allergic reactions: Hives, swelling, wheezing-seek urgent care.

How big is the eye risk, really? At doses at or below 5 mg/kg/day, large cohort data guided by the American Academy of Ophthalmology show the risk is very low for the first 5-10 years and rises with long duration, high doses, or kidney disease. Screening detects early changes so you can stop before vision loss. The point is not to scare you-it’s to make the simple safety steps a habit so you reap the benefits for years.

Pregnancy and breastfeeding

• Pregnancy: For lupus and RA, continuing hydroxychloroquine during pregnancy often lowers flare risk and is associated with better outcomes. ACR and EULAR support continued use in most cases. Always confirm with your obstetric and rheumatology team.
• Breastfeeding: Only small amounts pass into milk; major societies consider it compatible. Watch baby for unusual fussiness or rash, and discuss any concerns early.

COVID-19: Not used for prevention or treatment. WHO and NIH retired it from COVID guidance years ago. If someone tells you to take it for COVID, ask for up-to-date sources.

Malaria: Hydroxychloroquine’s role is limited due to resistance patterns. For travel, you’ll likely be offered other options (e.g., atovaquone/proguanil, doxycycline). A travel clinic will tailor it to your destination.

Decision help: is hydroxychloroquine the right first step for RA/lupus?

• RA with mild-to-moderate activity: Often part of initial therapy, sometimes combined with methotrexate and sulfasalazine (“triple therapy”).
• Lupus: A cornerstone medicine; many people with SLE stay on it long term because it reduces flares and helps skin/joint symptoms.
• If disease is severe (e.g., major organ involvement in lupus), you’ll likely need additional therapies on top-steroids short-term, immunosuppressants, or biologics.

Checklists you can use today

Before you start

• Confirm your dose is ≤5 mg/kg/day of your actual weight.
• List your meds and ask your clinician or pharmacist to screen for QT risks, digoxin interaction, and antacid timing issues.
• Book a baseline eye exam (within the first year). If you have kidney disease or take tamoxifen, flag this so screening starts earlier.
• Set expectations: no instant relief-review progress at 3 months, not 3 days.

Every refill

• Re-weigh if your weight has changed; make sure dose still fits the 5 mg/kg/day rule.
• Scan your meds list for any new QT-prolongers or changes in heart/kidney medicines.
• Ask yourself: any new vision symptoms? If yes, bring forward your eye check.

If you notice a problem

• New visual symptoms: pause, call your prescriber, and get an ophthalmology review.
• Severe nausea/reflux: take with food, split doses, or ask about dose timing changes.
• Low blood sugar symptoms (and you’re on diabetes meds): check a glucose, treat the low, and call your clinician about dose coordination.
• Palpitations/fainting: seek urgent care-bring your meds list.

Mini-FAQ

• Can I stop hydroxychloroquine suddenly? Yes, there’s no withdrawal, but your disease can flare. Discuss a taper plan during stable periods.
• Do I need blood tests every month? Not usually. Baseline labs and periodic checks, plus eye screening on schedule, are the mainstays.
• Does it cause weight gain? Not typically. If your weight is changing quickly, think steroids or other meds, not hydroxychloroquine.
• Is G6PD deficiency a problem? Hydroxychloroquine is less risky than some antimalarials, but discuss your status with your doctor if you’re G6PD deficient.
• Can kids take it? Yes, in certain conditions (e.g., juvenile lupus), dosed by weight, under specialist care.
• What if I already have macular degeneration? You’ll need a careful risk-benefit talk and closer eye monitoring if you proceed.

Scenarios and trade-offs (so you can act)

• You’re 58 with RA on hydroxychloroquine 400 mg/day, weight 60 kg. That’s 6.7 mg/kg/day-above the target. Talk to your doctor about 200-300 mg/day or adding another DMARD to compensate.
• You’re 32, pregnant with lupus. You’re stable on 200 mg/day. Stopping risks a flare; continuing is usually recommended. Confirm with your obstetrician and rheumatologist.
• You have stage 3 kidney disease. Dose may need to be lower, and you should start annual eye screening sooner than 5 years.
• You’re on amiodarone and an SSRI. That’s layered QT risk. Your prescriber may choose a different plan or monitor your ECG.
• You started 4 weeks ago and feel nothing. Normal. Reassess at 12 weeks before calling it a failure.

Where this guidance comes from: Ophthalmology screening and dose thresholds reflect American Academy of Ophthalmology recommendations (Marmor et al.), with retinopathy risk tied to dose, duration, kidney function, and tamoxifen co-use. Rheumatology use in RA/SLE aligns with American College of Rheumatology and EULAR guidance. COVID-19 positions reflect WHO/NIH. In New Zealand, availability and regulatory notes track Medsafe and PHARMAC updates as of 2025.

Next steps / troubleshooting

• If you’re starting this month: Set a reminder for week 6 and week 12 to check improvements (morning stiffness minutes, number of painful joints, fatigue score). Bring those notes to your check-in.
• If you’ve been on it 5+ years: Book your annual eye screening if it’s not on the calendar.
• If your dose is borderline high for your weight: Ask about a small dose reduction or alternate-day dosing (e.g., 200 mg one day, 400 mg the next) to hit the target average-only if your doctor agrees.
• If you’re changing other meds: Re-run the interaction check (QT risk, digoxin levels, diabetes meds) with your pharmacist or prescriber.
• If pharmacy supply changes brand or look: Confirm strength (usually 200 mg), and ask if any scoring or coating changes affect splitting or timing.

One last thing: this medicine is a marathon, not a sprint. When the dose is right, the eye checks are on time, and you give it those first 12 weeks, hydroxychloroquine can quietly do a lot of heavy lifting-fewer flares, less steroid, more good days. That’s the point.