Diclofenac is a painkiller that is in a class of medications called the non-steroidal anti-inflammatory drugs (NSAIDs). This medication is sometimes sold over-the-counter (OTC), but although both diclofenac and alcohol are widely available, they are not completely safe to combine. Many NSAIDs are not safe to combine with alcohol, due to the way that these medications exert their effects on the human body.
One type of protein involved in the body's inflammation response, which also causes pain, is known as the cyclooxygenase-2 (COX-2) enzyme. NSAIDs like diclofenac prevent COX-2 from functioning, which prevents inflammation. They also prevent a structurally similar enzyme known as COX-1 from working, as well. COX-1 normally plays a role in protecting the gastrointestinal (GI) from stomach acids. Sufficient doses of this medication can therefore leave the stomach more open to damage from digestive acids.
Alcohol may damage certain bodily tissue, including the stomach and intestines. Taken together, diclofenac and alcohol can do more harm to the stomach than either substance taken alone. A single combination of the two may not lead to permanent damage, but large doses of either substance, taking them together for long periods of time, or taking them together frequently may harm the stomach and intestines.
Stomach bleeding and ulcers can result from repeatedly mixing diclofenac and alcohol. Sufficient bleeding may sometimes lead to blood loss via the stomach, as well as anemia, a weakened condition caused by the loss of blood and nutrients. Additionally, long-term tissue damage may develop, weakening the stomach and making it more easily damaged in the future.
This damage is thought to be caused by diclofenac and alcohol preventing the formation of fatty molecules called prostoglandins, which help to regulate stomach muscle contractions. COX enzymes trigger the creation of prostoglandins under normal conditions, but this action is prevented by diclofenac. Alcohol, in turn, may directly damage the stomach tissue, which is unable to repair itself without active COX enzymes.
Scientists have evaluated the combination of diclofenac and alcohol as carrying a moderate risk. The occasional mixing of small amounts of these compounds is not likely to cause long-term harm to the body, unless an individual is particularly sensitive to their effects. Repeated combinations of these substances, and high-dose mixtures may increase the potential harm that they can cause. In extreme cases, the bleeding resulting from this mixture may lead to death. Bloody stool, stomach pain, and heartburn are all signs of damage from this combination, and patients experiencing these symptoms are typically advised to consult a doctor.