Most pharmacies refuse to sell antibiotics without a prescription from a doctor.
If his cut is just a surface cut open to the air, then he should wash it well and cover it with a topical antiseptic, such as Betadyne for example. Topical antiseptics you can buy at the pharmacy without any prescription.
But if it's a deep wound, then he should see a medical doctor about it. Because he might need a prescription for antibiotics from the doctor.
A deep wound can lead to a very serious infection. And leaving it untreated is risky in terms of health.
-Anonymous