Diclofenac Increases Blood Pressure
Diclofenac causes an increase in blood pressure and should be avoided or withdrawn in patients with hypertension, particularly those with resistant hypertension. 1, 2
Mechanism and Clinical Evidence
NSAIDs, including diclofenac, interfere with blood pressure control through inhibition of renal prostaglandin synthesis, leading to sodium and water retention 2. The FDA drug label explicitly warns that diclofenac can lead to new onset of hypertension or worsening of preexisting hypertension 2.
Magnitude of Blood Pressure Elevation
The blood pressure increase with diclofenac is clinically significant:
- In hypertensive patients, diclofenac raised systolic BP by 8.5 mmHg and diastolic BP by 2.4 mmHg over 2 weeks 3
- In the MEDAL study, diclofenac was associated with statistically significant BP increases, though etoricoxib showed even greater effects 4
- Diclofenac caused virtually complete COX-2 inhibition over the entire dosing interval, corresponding to the highest increase in systolic BP among NSAIDs studied 5
- In ACE inhibitor-treated patients, diclofenac increased 24-hour systolic BP by 4.1 mmHg and reduced GFR by 9.9 mL/min 6
Comparative Risk Among NSAIDs
Diclofenac carries particularly high cardiovascular risk among NSAIDs 7, 8, 9. A Danish registry study found diclofenac was associated with a hazard ratio of 2.40 (95% CI 2.09-2.80) for death in post-MI patients 7. The AHA scientific statement concluded that cardiovascular risk is proportional to COX-2 selectivity, and diclofenac—despite being classified as "non-selective"—has strong COX-2 inhibitory properties 8, 9.
Clinical Management Recommendations
For Patients with Hypertension
NSAIDs, particularly diclofenac, should be avoided or withdrawn in patients with resistant hypertension 1. When clinically unavoidable:
- Use the lowest effective dose for the shortest possible time 7, 2
- Monitor blood pressure closely during initiation and throughout treatment 1, 2
- Recognize that adjustments to antihypertensive regimens may become necessary 1
Preferred Alternatives
If analgesics are necessary, acetaminophen may be preferable to NSAIDs in subjects with resistant hypertension, though it provides little anti-inflammatory benefit 1. For musculoskeletal pain in cardiovascular disease patients, consider topical agents (lidocaine, diclofenac, capsaicin) or less-sedating muscle relaxants 10.
Drug Interactions
Diclofenac may blunt the effects of antihypertensive medications, including:
Calcium channel blockers appear to maintain antihypertensive effects better than other drug classes when used concurrently with NSAIDs 4.
Additional Cardiovascular Concerns
Beyond blood pressure elevation, diclofenac increases risk of:
- Heart failure hospitalization (approximately 2-fold increase) 2
- Myocardial infarction and cardiovascular death 7, 8
- Fluid retention and edema 2
Common Pitfalls
- Assuming "non-selective" NSAIDs like diclofenac are safer than COX-2 inhibitors—diclofenac has strong COX-2 selectivity and comparable or greater cardiovascular risk 8, 5, 9
- Failing to monitor BP when initiating diclofenac in patients on stable antihypertensive regimens
- Overlooking over-the-counter NSAID use when evaluating resistant hypertension 1