What is Diclofenac?
Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that works by stopping the body's production of substances that cause pain, fever, and inflammation [1.2.1]. It has been used to treat a range of conditions, including mild to moderate pain, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and painful menstrual periods [1.2.1, 1.2.5]. It belongs to the same class of drugs as more common over-the-counter medications like ibuprofen and naproxen [1.2.1]. For years, it was a go-to prescription for potent pain and inflammation relief, considered more powerful than many of its counterparts [1.4.4, 1.7.3]. However, a growing body of evidence has illuminated serious risks associated with its systemic use (e.g., tablets, capsules, injections), leading to a significant shift in its prescription patterns [1.8.4].
The Cardiovascular Dangers of Systemic Diclofenac
The primary reason for the decline in prescribing oral diclofenac is its well-documented link to an increased risk of serious cardiovascular events [1.2.1]. Both the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have issued strengthened warnings regarding these dangers [1.6.1, 1.8.1].
Heart Attack and Stroke Risk
Numerous studies and regulatory reviews have consistently shown that people taking systemic diclofenac have a higher risk of heart attack and stroke compared to those who do not take NSAIDs [1.2.1, 1.3.7]. A major Danish study involving over 1.3 million users found that starting diclofenac was associated with a 50% increased risk of major adverse cardiovascular events within 30 days compared to non-users [1.3.2]. The risk was also 20% higher than for those starting ibuprofen and 30% higher than for those starting naproxen [1.3.2].
The EMA concluded that the cardiovascular risk profile of diclofenac is similar to that of selective COX-2 inhibitors, a class of drugs that has faced intense scrutiny for heart-related side effects [1.8.4]. The risk appears to increase with higher doses (150 mg/day) and long-term use, but studies have shown that the danger can emerge even within the first few weeks of treatment and at lower doses [1.3.2, 1.6.2, 1.8.4]. As a result, diclofenac is now contraindicated for patients with established ischemic heart disease, peripheral arterial disease, cerebrovascular disease, or congestive heart failure [1.8.5].
Significant Gastrointestinal Side Effects
Like other NSAIDs, diclofenac can cause serious gastrointestinal (GI) problems, including ulcers, bleeding, or perforations in the stomach and intestines [1.2.1, 1.4.7]. These events can occur at any time during treatment, often without warning, and can be fatal [1.2.5]. The risk is elevated in older adults, those in poor health, and individuals who consume large amounts of alcohol [1.2.1].
While some studies suggest diclofenac may have a slightly better GI profile than naproxen, it carries a significantly higher risk than other alternatives [1.7.1]. One analysis found that diclofenac initiation increased the risk of upper gastrointestinal bleeding by approximately 4.5-fold compared to non-use, and 2.5-fold compared to ibuprofen use [1.3.2]. This pronounced risk of GI complications further diminishes its appeal when safer options are available.
Comparison with Safer NSAID Alternatives
When considering pain management, healthcare providers now weigh the efficacy of a drug against its safety profile. While diclofenac is a potent anti-inflammatory, its risks often outweigh its benefits compared to other NSAIDs [1.7.3].
| Feature | Diclofenac (Oral) | Ibuprofen (e.g., Advil, Motrin) | Naproxen (e.g., Aleve) |
|---|---|---|---|
| Cardiovascular Risk | High: Significantly increased risk of heart attack and stroke [1.3.2, 1.3.3]. Similar risk to COX-2 inhibitors [1.8.4]. | Moderate: Risk increases at higher doses (above 1200mg/day) [1.7.6]. | Lower: Considered to have one of the most favorable cardiovascular safety profiles among NSAIDs [1.2.4]. |
| Gastrointestinal Risk | High: 4.5 times higher risk of upper GI bleeding compared to non-use [1.3.2]. | Moderate: 2.7 times higher risk of GI bleeding compared to non-use [1.4.1]. | High: Similar to diclofenac, carries a significant risk of GI side effects [1.3.2]. |
| Potency | High [1.4.4]. Often more effective for arthritis pain at 150 mg/day than standard doses of ibuprofen and naproxen [1.7.4]. | Moderate. Widely available over-the-counter for mild-to-moderate pain [1.4.4]. | Moderate. Longer-lasting effects than ibuprofen [1.7.2]. |
| Availability | Prescription only for oral forms [1.4.4]. | Available over-the-counter and by prescription [1.4.4]. | Available over-the-counter and by prescription [1.7.2]. |
The Role of Topical Diclofenac
It is crucial to distinguish between systemic (oral) and topical (gel, patch) diclofenac. Regulatory warnings about cardiovascular risk explicitly apply to systemic formulations [1.3.4]. Topical diclofenac, such as Voltaren gel, is absorbed through the skin, leading to much lower concentrations of the drug in the bloodstream [1.5.6].
Studies comparing topical and oral diclofenac have found that the topical form is associated with significantly fewer gastrointestinal and cardiovascular adverse events [1.5.2, 1.5.4]. While the most common side effect is localized skin irritation (like dryness or rash), it offers a much safer profile, making it a viable and often recommended alternative for localized pain, such as in osteoarthritis of the knee or hand, especially for older patients or those at higher risk for systemic side effects [1.4.2, 1.5.5, 1.5.6].
Conclusion
The prescription of oral diclofenac has been curtailed not because it is ineffective, but because it is demonstrably riskier than its alternatives. The consistent evidence linking it to a heightened risk of heart attack, stroke, and serious gastrointestinal bleeding has led regulatory bodies and medical professionals to reconsider its place in pain management [1.3.2, 1.6.4, 1.8.1]. For treating systemic pain and inflammation, NSAIDs with more favorable safety profiles like naproxen and low-dose ibuprofen are now preferred [1.2.4]. Meanwhile, topical diclofenac remains a valuable and safer option for managing localized musculoskeletal pain, successfully separating its localized benefits from its systemic dangers [1.5.2].
Authoritative Link: European Medicines Agency: Diclofenac-containing medicines [1.8.1]
