What's the rules for bringing liquid medicines on international flights?

The EU allows exceptions for medically necessary items:

"European Union (EU) Hand Luggage Rules and Restrictions:

-To protect passengers against the threat of liquid explosives, the European Union (EU) security rules restrict the amount of liquids that can be taken through security checkpoints.

-This applies to all passengers departing from airports in the EU regardless of the destination. This means that, at security checkpoints, both passengers and hand luggage must be checked for liquids in addition to other prohibited articles.

-Medicines and dietary requirements, including baby foods, for use during the trip may be carried in hand luggage. Proof may be requested"

This is from the Rome airport info, but the rules are pretty much the same for every EU country, except for possibly the UK. I recommend that her brother just bring along any doctor's notes/documentation in case he is asked for proof.

I don't know the rules for Italy, but for departures from US airports, the TSA allows all medications, whether liquids, pills, vials, creams, syringes, needles or whatever. For liquids that are more than the 3.4 ounce limit, all you need to do is to tell the screener that you have liquid medication in larger quantities. They will take a look and let you go on. It may be required to show a doctor's note or a prescription label for the items in question.

I travel with a number of medications, and I have never been asked for any such documentation in the US, but it may be more frequent in EU countries.

I cannot imagine that Italian security would forbid taking life saving medication on board.

The security rules are probably the same for most EU airports, and I imagine there must be some websites that detail the EU requirements. I did not happen to find any, but may not have used the right kind of search terms.

Good luck.

There is no problem for passengers who need to carry prescribed medications with them. Both the TSA and all EEC countries follow the same rules. The only difference are that the US rules are in fluid ounces and the European ones are in millilitres.

I advise you to ensure that the medications are in their original wrappers and that a letter from the prescribing doctor accompanies the passenger to explain the need for this particular medication.

Security staff at airports are well used to dealing with this sort of thing. Just let them know what you are carrying as you arrive at the scanner. They will be helpfull.