I don't know if one can walk into a pharmacy in another country and get DHT with a prescription. It probably depends on the country, perhaps easier in some places than others. Even so, transporting it back into Israel could be considered trafficking, even with a prescription. At least, that's the case in Canada: it would be illegal for me to say, buy DHT in Mexico and then bring it home with me, despite a prescription. If your brother manages to buy DHT I would strongly recommend that he not carry it across any borders unless you know this is legal.

It sucks that this is such a hassle!