Diclofenac (Diclofenac sodium) – Patient-Friendly Medicine Information (Australia)

Diclofenac is a widely used non-steroidal anti-inflammatory drug (NSAID) used to help relieve pain and reduce inflammation. It is available in different forms (for example tablets, gels, and other topical options), and different strengths may apply depending on the product. This page explains how diclofenac works, when it’s typically used, what to expect from how it behaves in the body, and important safety information for people in Australia.

Basic product information

How diclofenac works (mechanism of action)

Diclofenac works by reducing the production of prostaglandins—chemicals in the body that contribute to pain, fever, and inflammation. Like other NSAIDs, diclofenac primarily inhibits cyclooxygenase (COX) enzymes (COX-1 and COX-2). By lowering prostaglandins:

• pain signals are reduced
• inflammation is decreased
• swelling and stiffness may improve

Diclofenac can provide meaningful symptom relief for many conditions, but it does not “cure” the underlying cause. If symptoms persist or worsen, medical assessment is important.

Pharmacokinetics (what happens to the medicine in the body)

While exact timing varies by formulation (for example, immediate-release vs slow-release, and by route of administration), the general pharmacokinetic behaviour of diclofenac includes the following:

• Absorption: Diclofenac is absorbed after oral administration and reaches peak levels in the blood within a few hours for many oral forms. Topical products lead to lower systemic absorption than oral medicines.
• Distribution: It binds to plasma proteins and can distribute to inflamed tissues.
• Metabolism: The medicine is extensively metabolised in the liver, mainly by enzyme systems responsible for drug breakdown.
• Elimination: Metabolites are excreted primarily by the kidneys and in smaller amounts via bile.

For people with liver or kidney impairment, exposure may increase, and careful use is required (see “Safety profile”). The best approach is to follow the directions on the specific product packaging and the advice of your pharmacist.

Typical uses and indications

Diclofenac is used for conditions where inflammation contributes to pain. Common indications include:

• Musculoskeletal pain such as sprains, strains, and back pain
• Joint and soft tissue inflammation related to injury or overuse
• Arthritis-related symptoms, including osteoarthritis and rheumatoid arthritis symptoms
• Painful inflammatory conditions where an NSAID is appropriate
• Topical use for localised pain (depending on product suitability and age limits)

Availability and wording of approved indications can vary with the exact product and strength. Always check the Consumer Medicine Information (CMI) or product label supplied with the medicine.

Timing: when and how to take it

Timing depends on the formulation and your symptoms. Below are general practical principles that apply to many diclofenac products.

Oral diclofenac (tablets/capsules)

• Follow the label dosing schedule. Some products are taken more than once daily; others have different release patterns.
• Use the smallest effective dose for the shortest possible time. This helps reduce side effects.
• Space doses evenly if multiple doses are required per day.
• If you miss a dose: take it when you remember unless it’s close to the next dose; don’t double up.

Topical diclofenac (gel)

• Apply to clean, dry skin over the painful area as directed on your product.
• Wash hands after application (unless your hands are the treatment area).
• Avoid broken skin and keep away from eyes and mucous membranes.
• Don’t cover with airtight bandages unless the product instructions specifically allow it.

If your pain is not improving after a short period (for example, a few days for acute injuries, or sooner for severe or concerning symptoms), seek advice from a healthcare professional.

Food interactions

Food can affect how quickly diclofenac is absorbed, particularly with oral forms. In many cases:

• Taking with food may help reduce stomach irritation.
• Swallow tablets whole unless the product instructions allow otherwise.
• Avoid taking on an empty stomach if you have a sensitive stomach or a history of NSAID-related indigestion.

Topical diclofenac has minimal direct food interaction because only small amounts reach the bloodstream compared with oral dosing. However, systemic precautions still apply if you are using additional oral NSAIDs.

Alcohol interactions

Combining diclofenac with alcohol can increase the risk of stomach irritation and gastrointestinal bleeding. Alcohol can also worsen side effects such as dizziness or drowsiness in some people.

• Best practice: limit alcohol while taking diclofenac.
• Avoid “heavy drinking”: risk increases substantially with higher alcohol intake.
• If you have a history of ulcers or GI bleeding: ask a pharmacist whether alcohol should be avoided completely.

Medicine interactions (important)

Diclofenac can interact with several medicines. These interactions may increase side effects or affect how medicines work. Below are common interaction categories. This is not a complete list—always review your full medication list with a pharmacist.

Interactions to watch closely

• Other NSAIDs (for example ibuprofen, naproxen, aspirin for pain): using more than one NSAID increases gastrointestinal and kidney risks.
• Anticoagulants (blood thinners) such as warfarin, or medicines like apixaban/rivaroxaban: NSAIDs may increase bleeding risk.
• Antiplatelets (for example clopidogrel): bleeding risk can increase.
• Selective serotonin reuptake inhibitors (SSRIs) and other antidepressants that affect serotonin: risk of GI bleeding may increase.
• Corticosteroids (for example prednisone): may increase stomach ulcer/bleeding risk when combined with NSAIDs.
• Diuretics (water tablets) and medicines affecting kidney function: the combination can increase kidney strain in some people.
• ACE inhibitors / ARBs (common for blood pressure/heart conditions): can increase risk of kidney impairment when combined with NSAIDs (especially with dehydration).
• Lithium: NSAIDs may raise lithium levels, increasing toxicity risk.
• Methotrexate: NSAIDs can increase methotrexate levels, potentially causing harm.
• Digoxin: interactions may affect digoxin levels.

If you take any of the above medicines, you should not assume diclofenac is safe for you—speak with your pharmacist before use. This is especially important if you have existing kidney disease, a history of ulcers, or heart disease.

Dosing guidance (general)

Dosing depends strongly on the specific product (strength and formulation) and the condition being treated. Always use the dose written on the product packaging or the instructions provided by your pharmacist.

General dosing principles

• Start low and adjust if needed within the limits of the product directions.
• Use the shortest effective course.
• Do not exceed the maximum daily dose stated for your product.
• Topical and oral products are not interchangeable—do not increase oral dose because you used a topical product.

Example dosing patterns (varies by product)

Some oral diclofenac products are taken one to three times daily depending on whether they are immediate-release or sustained-release. Topical diclofenac gels are applied in measured amounts several times per day as directed on the label.

Because exact dosing varies, the safest approach is to follow the instructions included with your specific brand and strength. If you’re unsure, contact your pharmacist for guidance.

Safety profile and precautions

Diclofenac can be effective, but it carries important risks typical of NSAIDs. Your risk depends on dose, duration, age, medical history, and other medicines.

Seek urgent help if you experience

• signs of an allergic reaction (swelling of face/lips, wheezing, severe rash)
• black/tarry stools, vomiting blood, or severe stomach pain
• chest pain, sudden shortness of breath, weakness on one side, or trouble speaking
• unexplained reduced urination or signs of kidney trouble

Common side effects

• indigestion, nausea, abdominal discomfort
• headache, dizziness
• skin irritation for topical products (redness, dryness)

Gastrointestinal (GI) risks

NSAIDs—including diclofenac—can increase the risk of stomach and intestinal ulcers, bleeding, and perforation. The risk is higher if you:

• have a history of peptic ulcer disease or GI bleeding
• use higher doses or take it for longer periods
• are older (risk generally increases with age)
• take other medicines that raise bleeding risk (for example anticoagulants, antiplatelets, corticosteroids, SSRIs)

Cardiovascular risks

NSAIDs can increase the risk of serious cardiovascular events (such as heart attack or stroke), particularly with higher doses and longer duration. People with existing heart disease, stroke history, or significant cardiovascular risk factors should use diclofenac with extra caution and seek advice from a healthcare professional.

Kidney risks

Diclofenac may affect kidney function, especially if you’re dehydrated or have kidney disease, heart failure, or use diuretics. Staying hydrated and avoiding unnecessary additional NSAIDs can reduce risk.

Liver and blood pressure considerations

• Liver: rare liver problems can occur. Stop and seek advice if you develop yellowing of the skin/eyes or severe unexplained fatigue with dark urine.
• Blood pressure and fluid retention: NSAIDs can worsen fluid retention and raise blood pressure in some people.

Topical product skin safety

With topical diclofenac, most side effects are local to the skin. Avoid using on damaged skin and wash hands after use. If you develop widespread rash or severe skin reaction, stop and get advice.

Practical use tips (how to get better results safely)

• Use the lowest effective dose for the shortest time.
• Consider topical first for localised, mild-to-moderate aches—topicals may have lower systemic exposure.
• Protect your stomach: take oral diclofenac with food if you get indigestion.
• Avoid stacking NSAIDs: don’t combine with ibuprofen, naproxen, or other NSAIDs.
• Stay hydrated, especially if you’re older or unwell.
• Know your red flags: stop and seek help if bleeding symptoms or breathing/swelling occurs.
• Don’t apply topical products over large areas or under occlusive dressings unless directed.
• Track symptom changes: if pain worsens, new symptoms appear, or it doesn’t improve, seek advice.

Alternative options

If diclofenac isn’t suitable, there may be other ways to manage pain and inflammation. Alternatives can include other NSAIDs, paracetamol (acetaminophen), or non-drug strategies. Which option is best depends on the cause of pain and your health profile.

Possible alternatives (not all are suitable for everyone)

• Paracetamol for pain relief (does not provide the same anti-inflammatory effect as NSAIDs).
• Other topical NSAIDs (for example ibuprofen-based gels) for localised pain.
• Other oral NSAIDs (selected by a pharmacist or doctor based on your risk factors).
• Non-medicine approaches such as rest, physiotherapy, heat/ice therapy, supportive braces, and stretching.

If you’re currently taking diclofenac and want to switch, it’s usually best to consult a pharmacist to confirm safe timing, especially when changing from one NSAID to another.

Market and legal context in Australia

In Australia, medicines are regulated by the Therapeutic Goods Administration (TGA). Diclofenac products may be supplied as different brands and strengths, and availability can vary depending on whether the product is considered suitable for supply under different scheduling categories (for example, some topical products may be available without a prescription while others require prescription status).

Product brands, pack sizes, and indicated use can differ. Always use the exact product you purchased and check the label for dosing instructions and warnings. For the most accurate and up-to-date information, refer to:

• the Consumer Medicine Information (CMI) included with the product
• the TGA database or related medicine resources
• your pharmacist for personalised guidance based on your history and other medicines

Recent guidance and monitoring (high-level)

Over recent years, healthcare guidance has continued to emphasise safer NSAID use:

• use the lowest effective dose for the shortest possible duration
• careful screening for GI bleeding, kidney, and cardiovascular risk factors
• avoid combining NSAIDs unless specifically advised
• consider non-drug therapies and topical options for localised pain where appropriate

If you have risk factors (such as prior ulcers, kidney disease, heart disease, or you’re on blood thinners), talk with your pharmacist early to help choose the safest pain relief plan.

Delivery and availability

Diclofenac availability can differ by form and strength. In our online pharmacy, we aim to provide access to commonly used diclofenac products (including topical options) where permitted by Australian regulations. Availability may also depend on manufacturer supply and the specific product category.

• Home delivery: available in many areas across Australia, depending on shipping services.
• Dispatch times: vary based on stock levels and your delivery location.
• Packaging: medicines are dispatched in secure, labelled packaging.
• Customer support: our pharmacists can help you understand dosing instructions and key safety considerations.

To ensure you receive the correct product, confirm the product name, strength, and form on your order before checkout.

FAQ

Is diclofenac safe for everyone?

No. Diclofenac is not suitable for everyone. People with a history of NSAID allergy, asthma triggered by NSAIDs, stomach ulcers or bleeding, significant kidney disease, certain cardiovascular conditions, or those taking specific interacting medicines may need to avoid diclofenac or use it with extra caution.

Can I take diclofenac with paracetamol?

Paracetamol is often used alongside NSAIDs for pain relief, but it’s important to follow the dosing instructions on both products. If you have liver disease or drink alcohol heavily, discuss safety before using paracetamol.

What is the difference between topical and oral diclofenac?

Topical diclofenac is applied to the skin over the painful area and typically results in lower systemic exposure than oral dosing. Oral diclofenac affects the whole body and may be used for more widespread or severe pain, but it carries higher risk for some side effects such as GI and cardiovascular events.

How quickly will diclofenac start working?

Many people notice pain relief within hours for oral forms. Topical products may take longer and often provide gradual improvement over the first day or two, depending on the condition and severity of symptoms.

Should I avoid exercise while using diclofenac?

Often, light movement is beneficial for many musculoskeletal injuries and arthritis symptoms. However, avoid activities that significantly worsen pain or cause re-injury. Diclofenac can reduce pain, so be mindful not to overdo activity. If symptoms are severe or worsening, seek advice.

Can I drink alcohol while taking diclofenac?

It’s best to limit alcohol. Alcohol may increase the risk of stomach irritation and gastrointestinal bleeding. Avoid heavy drinking while using diclofenac.

What if my pain doesn’t improve?

If pain persists beyond a short course, worsens, or you develop new symptoms (such as fever, redness, swelling that spreads, weakness, or numbness), stop and seek medical advice. Persistent or severe pain may need a different assessment.

Are there signs of overdose?

Overdose can be dangerous. Seek urgent help if you believe you’ve taken too much diclofenac, or if you develop symptoms such as severe dizziness, persistent vomiting, unusual bleeding, severe stomach pain, or difficulty breathing.

How should I store diclofenac?

Store according to the label (usually at room temperature, away from heat and moisture). Keep out of reach of children. For topical products, check whether refrigeration or special storage is recommended.

Can I use diclofenac during pregnancy or breastfeeding?

NSAID use in pregnancy and breastfeeding must be considered carefully. Because diclofenac safety can vary by trimester and individual circumstances, consult a pharmacist or healthcare professional for tailored advice before use.

Summary

Diclofenac (diclofenac sodium) is an NSAID medicine used to relieve pain and inflammation associated with many conditions, including musculoskeletal problems and arthritis symptoms. It works by reducing prostaglandin production, which helps lower pain and swelling. While it can be effective, it carries important safety considerations—particularly risks to the stomach, kidneys, and cardiovascular system. The safest approach is to follow the specific product directions, use the lowest effective dose for the shortest time, avoid combining with other NSAIDs, and seek advice if you have risk factors or experience warning signs.