Stay hard longer
I just googled "viagra nz" and found a medsafe article that says "you can only get viagra with a doctors prescription or from a pharmacist trained to supply sildenafil without a doctors prescription".
it's easier with a prescription, but some pharmacies will, but you have to answer some health questions and they check your blood pressure. this little checkup should be free. last year i found one chemist on K rd wanted to charge me, another was free. i think it was 'Newton Pharmacy' that was free. it was a while ago.
Put an advert on Trade me. Lol.
It's super easy to get generic Viagra from a pharmacist. I was curious and got some a year ago. Turns out 1 pill is waaaay too much for me and numbs the shit out of my face AND hard as fuck dick.
Given that it can have some quite strong effects, it's advisable to get at least a pharmacist to check you out.