Prescription can be free to some people in the UK. From the NHS website:
You can get free NHS prescriptions if, at the time the prescription is dispensed, you:
are 60 or over
are under 16
are 16-18 and in full-time education
are pregnant or have had a baby in the previous 12 months and have a valid maternity exemption certificate (MatEx)
have a specified medical condition and have a valid medical exemption certificate (MedEx)
have a continuing physical disability that prevents you going out without help from another person and have a valid MedEx
hold a valid war pension exemption certificate and the prescription is for your accepted disability
are an NHS inpatient
You're also entitled to free prescriptions if you or your partner – including civil partner – receive, or you're under the age of 20 and the dependant of someone receiving:
Income Support
Income-based Jobseeker's Allowance
Income-related Employment and Support Allowance
Pension Credit Guarantee Credit
Universal Credit and meet the criteria
If you're entitled to or named on:
a valid NHS tax credit exemption certificate – if you don't have a certificate, you can show your award notice; you qualify if you get Child Tax Credits, Working Tax Credits with a disability element (or both), and have income for tax credit purposes of £15,276 or less
a valid NHS certificate for full help with health costs (HC2)