Chloroquine (Chloroquine Phosphate) – Patient Information (UK)

Chloroquine, supplied as chloroquine phosphate, is a medicine that has been used for decades to treat certain parasitic infections and, in some cases, immune-related inflammatory conditions. In the UK, its availability and recommended use depend on current clinical guidance, local supply, and the resistance patterns of the parasite in question. This page provides patient-friendly information to help you understand how chloroquine works, how it is taken, and what to expect regarding safety and interactions.

1) Basic Product Information

• Medicinal name: Chloroquine (as chloroquine phosphate)
• What it is: Antimalarial and anti-inflammatory medicine
• How it may be supplied: Tablets (strengths vary by manufacturer)
• Common uses: Treatment of malaria due to susceptible parasites; other selected inflammatory indications under specialist guidance
• ATC code: P01BA01

The most appropriate use of chloroquine depends on the infection type, the country visited (if applicable), and local resistance patterns. Your clinician or travel clinic will advise whether chloroquine is suitable for your situation.

2) How Chloroquine Works (Mechanism of Action)

Chloroquine’s antimalarial effect comes from interfering with the parasite’s ability to break down haemoglobin. When malaria parasites invade red blood cells, they ingest haemoglobin and convert it into forms that they can digest. Chloroquine blocks a key step in this process by preventing the parasite from safely detoxifying haem (a breakdown product of haemoglobin).

• Inside the parasite: Chloroquine accumulates in the acidic food vacuoles of the malaria parasite.
• Blocks detoxification: It prevents haem from being converted into the non-toxic haemozoin form.
• Result: This leads to toxic build-up within the parasite and parasite death.

For inflammatory uses, chloroquine can also affect the immune response by altering lysosomal function and reducing the activity of certain immune signalling pathways. This contributes to its anti-inflammatory properties in selected conditions.

3) Pharmacokinetics (Absorption, Distribution, Metabolism, Excretion)

Pharmacokinetics describes what the body does to a medicine—how it is absorbed, distributed, broken down, and removed.

Absorption

Chloroquine is generally well absorbed after oral doses. Absorption can vary between individuals.

Distribution

• Wide distribution: Chloroquine distributes throughout the body, including tissues.
• Long retention: It tends to remain in tissues for a long time.
• Crosses barriers: It can cross into the bloodstream and may distribute beyond the initial site of infection.

Metabolism

Chloroquine is metabolised in the liver. Liver function is therefore relevant for safe use and dosing decisions.

Elimination

• Excretion: It is removed from the body over time through metabolic processes and excretion (including via urine).
• Half-life: Chloroquine has a relatively long half-life, which means effects (and side effects) may persist after the dose schedule ends.

Because chloroquine remains in the body for a long time, adverse effects—especially those involving the heart or eyes—require careful monitoring in prolonged use.

4) Typical Use and Indications

4.1 Malaria treatment (where chloroquine is effective)

Chloroquine may be used to treat malaria caused by certain chloroquine-susceptible parasites. However, resistance is widespread in many regions, so it is not appropriate for all malaria types or travel destinations. The choice of treatment should follow up-to-date recommendations.

4.2 Inflammatory/immune-related conditions (selected use)

In some countries, chloroquine has also been used for certain inflammatory disorders (for example, some forms of malaria- or autoimmune-related conditions). In the UK, the decision to use chloroquine for these indications depends on the diagnosis, severity, and suitability compared with alternatives.

If your chloroquine is for a non-malaria indication, your healthcare team will tailor the dose and monitoring schedule.

5) Dosing and Timing

Dosing depends on the reason for use, your weight, the severity, and your overall health (including liver and heart health). Always follow the dosing plan given by your healthcare professional and the instructions on your specific medicine package.

5.1 Common malaria dosing concepts (general information)

For malaria, dosing schedules can vary depending on parasite susceptibility and local guidelines. Treatment regimens often involve an initial dose followed by additional doses over a set number of days. The total dose is calculated to clear parasites while reducing the risk of resistance and side effects.

Important: Do not self-adjust dosing. If symptoms worsen or do not improve, seek medical advice promptly.

5.2 How to take chloroquine

• Take by mouth with water.
• Try to take at the same time(s) each day if your schedule is repeated.
• Complete the full course for infections, unless advised otherwise.

5.3 Missed dose

If you miss a dose and it is close to the next scheduled dose, do not double it. Take advice from a pharmacist or your prescriber for guidance based on your schedule.

6) Food Interactions and How to Take It With Meals

Food can affect how some medicines are absorbed. For chloroquine, taking it with food may help reduce stomach upset for some people.

• General tip: Taking your dose with a meal or a snack can be easier on the stomach.
• Consistency: Try to use a consistent approach (e.g., always with meals) unless your healthcare professional advises otherwise.

If you experience nausea or abdominal discomfort, ask your pharmacist about whether taking it with food is suitable for your specific regimen.

7) Alcohol and Medicine Interactions

7.1 Alcohol

Alcohol can affect your liver and may worsen dehydration, nausea, and dizziness—all of which can be relevant during infections and while taking other medicines. For these reasons, it is generally recommended to avoid or limit alcohol while taking chloroquine, especially if you feel unwell.

7.2 Interactions with other medicines

Chloroquine can interact with other medicines, particularly those that affect the heart’s rhythm. It may also interact with medicines processed by the liver.

Tell your pharmacist or healthcare professional if you take any of the following:

• Medicines that prolong the QT interval (heart rhythm medicines or some antibiotics/antidepressants/antipsychotics)
• Other antimalarials or medicines used for fever/infections
• Digoxin or other heart-related medicines
• Anti-seizure medicines (antiepileptics)
• Some medicines for nausea or mood that can affect heart rhythm
• Medicines affecting blood sugar, as malaria and illness can influence glucose levels

Do not start, stop, or change doses of other medicines without advice. If you are travelling, also consider medicines you may have from other countries.

8) Safety Profile: Side Effects and When to Get Help

Like all medicines, chloroquine can cause side effects. Many are mild and temporary, but some can be serious. The risk can increase with higher doses, long duration of use, and certain interactions (especially with other QT-prolonging medicines or in people with heart conditions).

8.1 Common side effects

• Nausea
• Stomach upset
• Headache
• Loss of appetite
• Dizziness
• Skin reactions (less commonly mild rashes)

8.2 Serious side effects (seek urgent advice)

Contact urgent medical services or seek emergency care if you experience:

• Signs of an allergic reaction: swelling of the face/lips, difficulty breathing, severe rash
• Heart symptoms: fainting, severe dizziness, fast or irregular heartbeat, chest pain
• Vision changes: blurred vision, unusual light sensitivity, vision loss
• Severe or persistent vomiting or inability to keep fluids down
• Neurological symptoms: confusion, severe weakness, seizures

8.3 Eye and skin risk with longer use

With prolonged use, chloroquine may affect the eye (retinopathy) and the skin. This is why monitoring is essential if chloroquine is taken for non-malaria, long-term indications. Even when used for infections, clinicians may advise monitoring if courses repeat or extend.

8.4 Heart rhythm risk

Chloroquine can affect heart rhythm. People at higher risk include those with known heart rhythm problems, electrolyte imbalances (low potassium/magnesium), significant dehydration, or those taking other QT-prolonging medicines.

9) Practical Use Tips (How to Take It Safely)

• Use the correct strength: Make sure you have the exact product and strength prescribed/recommended for you.
• Follow the schedule: Malaria regimens often rely on strict timing to be effective.
• Stay hydrated: Especially if you have fever or vomiting due to infection.
• Watch for side effects early: If you notice vision changes, unusual dizziness, or palpitations, seek medical advice promptly.
• Avoid extra “immune boosters” without checking: Supplements and herbal products can sometimes interact with medicines or affect your health during infections.
• Keep a record: Note the date/time of doses and any symptoms so you can report them accurately.

If you are taking chloroquine for long-term inflammatory use, stick to your follow-up appointments and any eye/skin monitoring recommended by your clinician.

10) Safety in Special Circumstances

Pregnancy and breastfeeding

The safety of chloroquine in pregnancy and breastfeeding depends on the indication and overall risk-benefit assessment. Malaria in pregnancy can be dangerous, so treatment decisions often differ from those for non-infectious conditions. Always obtain advice from a healthcare professional if you are pregnant, trying to conceive, or breastfeeding.

Liver disease

Because chloroquine is metabolised by the liver, dose suitability may change in people with liver impairment.

Heart disease or rhythm problems

People with a history of rhythm disturbances, known QT prolongation, or heart failure may require extra caution and monitoring.

Children

Chloroquine dosing in children is typically weight-based and must be carefully calculated. Keep medicine out of reach of children and store safely.

11) Alternative Options

Alternatives depend heavily on the reason for taking chloroquine and, for malaria, the parasite type and resistance in the region. Common alternatives may include other antimalarials such as:

• Artemisinin-based combination therapies (ACTs) for many forms of malaria where resistance makes chloroquine unsuitable
• Other antimalarial medicines used in specific settings (choice depends on local guidance and susceptibility patterns)

For inflammatory/immune-related conditions, alternative medicines may include other disease-modifying or anti-inflammatory therapies, chosen based on the specific diagnosis and monitoring plan. Your clinician can advise what is most suitable for you.

12) UK Market and Legal/Regulatory Context

In the United Kingdom, the use, supply, and prescribing/dispensing of medicines are regulated to ensure patient safety and public health. Chloroquine may be subject to availability constraints and clinical suitability criteria. For malaria, guidelines are updated to reflect resistance patterns and best evidence.

For infection management, national and international guidance influences recommended first-line treatments. For long-term inflammatory use, the UK monitoring framework for vision and other risks is relevant to ensure safe ongoing therapy.

Note: Availability and brand/manufacturer options can vary. If you are unable to obtain your medicine, a pharmacist can advise on current UK availability or suggest a suitable alternative pathway.

13) Recent Guidance and Resistance Considerations (UK-Relevant)

Malaria treatment guidance continues to evolve as resistance patterns change. In many areas of the world, malaria parasites have developed resistance to chloroquine, meaning chloroquine is not recommended for those resistant forms. If you were exposed to malaria while abroad, your travel destination and timing of illness are especially important.

• Check region suitability: Confirm whether chloroquine is effective for the specific malaria type and region.
• Follow local NHS/clinical guidance: Treatment choices should align with current recommendations.
• Do not rely on past regimens: Resistance patterns can change over time.

If you have fever, chills, or flu-like symptoms after travel to a malaria-risk area, seek medical assessment promptly—early treatment is critical.

14) Delivery and Availability in the UK (Online Pharmacy)

Availability of chloroquine products may vary due to demand, supply chain factors, and clinical control measures. When you order from an online pharmacy, you may be asked to confirm certain details during checkout to ensure the medicine is suitable for you and that safe dispensing requirements are followed.

What to expect

• Order processing: Usually processed promptly during business hours.
• Delivery times: Delivery options depend on the pharmacy’s logistics network and local availability.
• Packaging: Medicines are delivered in tamper-evident packaging with clear labelling.

If the exact strength or brand is not available, the pharmacy may offer the closest appropriate alternative where permitted and clinically acceptable. Always check the label and leaflet when the medicine arrives.

15) Chloroquine FAQ

How long does chloroquine take to work?

For malaria, improvement may begin within 24–48 hours after starting effective therapy, but this can vary. If fever persists or symptoms worsen, contact a healthcare professional urgently for reassessment and possible change of treatment.

Can I take chloroquine with food?

Many people find that taking chloroquine with food reduces stomach upset. Try to take it consistently with meals or as advised by your pharmacist.

Is chloroquine still used for malaria?

Yes, but mainly for malaria types that remain susceptible to chloroquine. Because resistance is common in many regions, chloroquine is not appropriate everywhere. Treatment recommendations depend on where exposure occurred and the suspected malaria species.

What should I do if I miss a dose?

Do not double up. The right action depends on your dosing schedule. Ask a pharmacist or your healthcare professional for advice tailored to your regimen.

What side effects are most important to watch for?

Seek urgent advice for signs of heart rhythm problems (fainting, severe dizziness, palpitations), serious allergic reactions, and vision changes. Contact a clinician promptly if side effects are severe or persistent.

Can I drink alcohol while taking chloroquine?

It’s generally best to avoid or limit alcohol while you’re taking chloroquine, particularly during an infection. Alcohol may increase the risk of side effects and may worsen dehydration or stomach upset.

Are there medicine interactions I should know about?

Yes. Tell your pharmacist if you take medicines that affect heart rhythm (QT prolongation), digoxin, anti-seizure medicines, antidepressants/antipsychotics, certain antibiotics, or any other regular medicines. Interactions can be serious, so checking is important.

How is chloroquine stored?

Store as directed on the package leaflet. Keep out of sight and reach of children, and protect from moisture/heat where specified.

Summary

Chloroquine (chloroquine phosphate) is a medicine used for certain malaria infections and selected inflammatory conditions. It works by interfering with the malaria parasite’s ability to detoxify haem and may also reduce immune-related inflammation in specific settings. Its long presence in the body means monitoring and cautious use are important—especially regarding potential effects on the eyes and heart rhythm. If you are considering chloroquine for malaria, ensure it is suitable for the malaria type and region. Always follow the dosing schedule provided by your healthcare professional and seek urgent help for serious symptoms such as vision changes, allergic reactions, or signs of abnormal heart rhythm.