To determine the prevalence of self-medication in nursing students and their related factors, a transversal, descriptive study was performed on a sample of 378 nursing students. A total of 73.8% of the sample declared having used off-prescription drugs during the last month (2.84;2.26–3.58). A total of 28.9% said they did this because they are familiar with the health problem and its pharmacological solution and 25% deemed that it was a mild health problem. Drugs most commonly used off-prescription were analgesics in 88.91% (3.63;2.74–4.80) of occasions. They were mainly recommended by the students’ family (1.31;1.03–1.65) on 58.12% of the cases. Students keep analgesics they take off-prescription in their home first aid kit (4.47;3.28–6.08; p < 0.001). Unlike other studies, 53.2% obtained off-prescription drugs from the home first aid kit (1.13;0.89–1.43; p < 0.001). In addition, they gave advice and recommend drugs they have taken to other people with similar symptoms (1.97;1.59–2.44). A total of 85.72% kept excess drugs after a treatment (6.00;4.50–7.99). Self-medication is related to the storage of unused medicines and giving advice on the use of drugs to other people, among other things. Self-medication of drugs among nursing students is high. Thus, it appears necessary to review the training on rational the use of drugs and responsible self-medication in the discipline’s curriculum.