You can still easily buy it here, but the over-the-counter pills are always mixed with other ingredients to make it more difficult to convert them into amphetamines.
E.g. Contac 600 Plus can be found in basically all drug stores and it has 120mg of Pseudoephedrine, 100mg Caffeine, 8mg Chlorpheniramine, and 0.4mg of Belladonna Extract. It sounds like it'll actually be illegal to import into Japan, since 120/(120 + 100 + 8 + 0.4) is over 10%, but I've previously just walked into a drug store and bought a packet.
Not for the ones you buy in Japan, since those are legal.
But, it's not unheard of to get randomly stopped by the police and searched, especially in touristy areas like train stations. Unless you're a Japanese citizen, you have to show ID, and although the searches are optional, most people agree to them.
For customs, usually a few people from each plane are searched.
Anecdotally, if you're a tourist, they're usually looking for medicine that was legal outside of Japan, but illegal within Japan, with small amounts leading to being detained for 23 days (like in this blog post). And if they decide to prosecute you, you'd probably get a suspended sentence (so no prison time), but you'd get deported and a temporary ban from coming back to Japan.
> with small amounts leading to being detained for 23 days (like in this blog post)
This seems ultimately like a very bad sales pitch for the tourism industry in Japan. I had thought I wanted to go to Japan but if I can accidentally, without malice, be thrown in a prison for 20 days that seems like a bad system.
I can't imagine the international relations of the ruling classes of various countries to the UAE would be trending in a positive direction if they arrested and punished people for walking off a plane with airplane bottles of alcohol.
Probably the same thing you do in the states if you have high blood pressure: make do with lesser medications, pain killers, lots of liquids, and push through it.
Warning: This is not medical advice, I am a nerd on the internet not a doctor
For what it is worth different countries have vastly different recommendations for HBP and these drugs. I recommend discussing with the pharmacists in your country.
In the US I have been told it's a strict "never", in Ireland I was told that it wouldn't have a measurable effect on blood pressure. I've also measured my personal blood pressure (pre-hypertension to stage 1) and have not been able to measure a difference in blood pressure.
E.g. Contac 600 Plus can be found in basically all drug stores and it has 120mg of Pseudoephedrine, 100mg Caffeine, 8mg Chlorpheniramine, and 0.4mg of Belladonna Extract. It sounds like it'll actually be illegal to import into Japan, since 120/(120 + 100 + 8 + 0.4) is over 10%, but I've previously just walked into a drug store and bought a packet.