OTC drugs such as multivitamins, multiminerals, cranberry and aspirin besides leading to antibiotic resistance and causing other health issues, may also affect lab test results, leading to possibly incorrect diagnoses, researchers have warned.
 

The study showed that dietary supplements and OTC drugs were more frequently used by middle-aged patients, especially women. These compounds, if consumed shortly before blood sampling, may cause changes in lab test results, thus leading to interpretation difficulties and possibly incorrect diagnoses, the researchers noted.

Moreover, the patients were also reluctant or did not feel the need to disclose the use of these drugs to medical or laboratory staff. "We hope that our survey helps to raise awareness about the need to educate patients about the potential effect of OTC drugs and dietary supplements on lab test results," said Ana-Maria Simundic, Professor at the Sveti Duh Clinical Hospital in Croatia.

"We would encourage clinicians and lab staff to engage more with their patients and ask them to direct questions about the use of various self-prescribed products," she added. For the study, published in the journal Clinical Chemistry and Laboratory Medicine, the team surveyed 18 European countries and anonymously surveyed 200 outpatients in each country. 

In total, 68 per cent of patients were regularly taking at least one OTC drug or dietary supplement. Vitamins (38 per cent), minerals (34 per cent), cranberry juice (20 per cent), acetylsalicylic acid (ASA) (17 per cent) and omega fatty acids (17 per cent) were the most commonly used in the study. The researchers stressed on the need of a multifaceted approach to draw attention to the issue using educational interventions which target both healthcare professionals and patients.