Pharmacy Situation
Tiene que tomarse una cada cuatro horas, is translated to 'You have to take one every four hours.'
It's about a prescription, in a pharmacy.
Does it have to be 'tomarse'? Why not just 'tomar'? like:
Tiene que tomar una cada cuatro horas
2 Answers
The tiene is refering to the pill, I think, rather than to the person taking the pill.
The pills have to be taken one every four hours.
Think about the English equivalent. Drug labelling is formal - you'd not likely see 'You have to take one every four hours.', rather 'To be taken one every four hours.', or similar.
It looks like they have tomar as a reflexive verb. I agree, I would put "Tiene que tomar una cada cuatro horas."