Users of non-steroidal anti-inflammatory drugs are at increased risk of venous thromboembolism, according to a new study published in the journal Rheumatology.

Non-steroidal anti-inflammatory drugs (NSAIDs) relieve pain and reduce inflammation. Millions of Americans take NSAIDs for musculoskeletal problems, sprains, strains, back pain headache and painful menstruation periods, as well as chronic conditions such as arthritis and lupus.

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Until now, the evidence for a link between NSAID use and venous thromboembolism has been limited.

NSAIDs - including drugs such as aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve) and celecoxib (Celebrex) - are known to be associated with the following side effects:

Some previous studies have linked increased risk of venous thromboembolism (VTE) - a condition that includes both deep vein thrombosis and pulmonary embolism - with NSAID use, but the evidence has been limited.

Fast facts about NSAIDs
  • At low doses, NSAIDs work as painkillers. To reduce inflammation, higher doses are needed
  • Over-the-counter NSAIDs should not be taken if the patient is already taking a prescription NSAID
  • No single NSAID is better or safer overall than any other NSAID.

Learn more about NSAIDs

For the new study, researchers from Bassett Medical Center, New York, performed a systematic review and meta-analysis of the available observational studies that evaluated risk of VTE in users and non-users of NSAIDs.

The researchers compared one cohort study and five case-control observational studies, which included a total of 21,401 VTE events. They found that NSAID users had an overall 1.8-fold increased risk of VTE compared with study participants who did not use NSAIDs.

"This is the first systematic review and meta-analysis of published observational studies assessing the risk of VTE among NSAIDs users," says lead author Patompong Ungprasert.

"There are some limitations, however," Ungprasert cautions, "such as the fact that all NSAIDs are evaluated as one group in this study but not all individual NSAIDs may increase the risk of VTE."

"Our results show a statistically significant increased VTE risk among NSAIDs users. Why NSAIDs may increase the risk of VTE is unclear. It is possibly related to COX-2 inhibition leading to thromboxane-prostacyclin imbalance. Physicians should be aware of this association and NSAIDs should be prescribed with caution, especially in patients already at a higher risk of VTE."

In other NSAID news, Medical News Today recently reported that regular use of NSAIDs may halve breast cancer recurrence in overweight women. Another 2014 study found that daily use of aspirin may reduce ovarian cancer risk by 20%.

And back in 2011, we reported that aspirin is associated with lower risk for liver cancer and death from liver disease.