I was already more than halfway to Tokyo when I realised I was carrying a stash of hardcore narcotics in my carry-on bag.
My stomach flipped as I made the unpleasant discovery while rifling through my bag during a brief stopover.
As images of Schapelle Corby and Banged Up Abroad flashed through my mind, I quickly shoved the contraband in a garbage bin at the gate, hoping like hell I'd get away with it. I did.
The illicit item in question was a mostly used packet of Codral Original Cold & Flu tablets containing codeine and pseudoephedrine, two substances strictly outlawed in Japan.
My intentions were innocent: I had a cold before leaving Australia and brought the Codral to the airport for one last dose before the flight, with a plan to toss out what was left before boarding. But I'd totally forgotten.
I'm not sure what would have happened if I'd been caught with the Codral at Tokyo airport. I am sure I don't want to find out.
Because Japan is one of many popular travel destinations — also including the United States, Thailand and Greece — that have surprisingly hardline attitudes towards common medications legally available in Australia and New Zealand, including over-the-counter drugs.
And in those countries, these seemingly innocuous items could land travellers in big trouble, including jail, news.com.au reports.
"Even medications that are legal in Australia can attract heavy fines overseas or, in extreme cases, jail sentences in prison environments that might be much harsher than at home," Abigail Koch, travel insurance expert at comparethemarket.com.au, said.
"In these instances, travel insurance may not cover you if you are carrying or using drugs that are classified as illegal overseas.
"If you have a medical condition, it is important to talk to your doctor to see if there are alternative medications you can take and to get a doctor's letter or prescription before travelling. It's also crucial to disclose any pre-existing medical conditions and current medical treatments to your travel insurer, and ensure you're covered for any health issues that may arise while travelling."
Here are the common medications that could get us in trouble in some of our favourite overseas destinations, according to comparethemarket.com.au.
But wherever you're heading, it's always worth checking in with the embassy/consulate, speaking with a doctor, and understanding the ingredients in your medication.
And for heaven's sake, don't accidentally pack anything considered illegal when you step off the plane.
The US bans addictive narcotics such as antidepressants and sleeping pills without a doctor's note, so if you're relying on sleeping pills to get through the long-haul flight, plan accordingly.
The US Customs and Border Protection says medicines containing potentially addictive drugs or narcotics need a written statement from a doctor. These drugs should also be kept in their original packaging with no more than a 90-day supply.
UNITED ARAB EMIRATES
There are some really innocent products on the blacklist here, including common contraceptive pills and children's Panadol.
Possession of any drugs that are classified as illegal can lead to imprisonment in many Gulf countries. The UAE specifically bans anything containing codeine, Valium or Ritalin, as well as medicine to treat HIV/AIDS and hepatitis.
comparethemarket.com.au found there are 70 banned medicines in the UAE, including the Diane 35 and 36 contraceptive pills, some nicotine lozenges and children's Advil and Panadol.
For medication necessary for emergency or health reasons, travellers may be allowed to carry 30 days of treatment if they have prior permission from the UAE Ministry of Health, a valid prescription and a valid certificate from the New Zealand health authority.
Restrictions apply to some drugs that contain codeine. Medication to treat Attention Deficit Hyperactivity Disorder (ADHD), which is normally prescribed by a doctor in New Zealand, is also considered a controlled substance in Thailand.
In Hong Kong, it is illegal to be in possession of sleeping tablets and medications used in treating certain conditions, such as erectile dysfunction or anxiety, without a doctor's note.
Singapore considers medicinal chewing gum, like nicotine gum, to be a prohibited substance. It also bans anti-anxiety pills, sleeping pills and strong painkillers without a licence.
Common medicines, such as those used to treat diabetes or high cholesterol, are banned if you have more than a three-month supply.
Japan is one of the friendliest countries you can visit but it has very strict rules on what's allowed to be carried in and out of the country.
Dexamphetamine, which is used to treat ADHD, and pseudoephedrine, which is found in some cold and flu tablets, can be a reason for detainment.
Medicines containing codeine or morphine need a narcotic certificate before entering the country.
Don't enter China without a doctor's note for every medication you're carrying. Any amount of medication above a seven-day supply needs to be verified by a prescription.
This note should outline what the drug is being used for and the quantities required.
It's also important to bring a copy, as customs may want to keep a copy of your prescription.
Greece has stricter rules surrounding codeine than other European countries. Codeine is allowed only with a prescription stating what it is, how much is taken and that it is for personal use only.
Medications that are classified as a controlled substance (narcotic) need approval from the Narcotic Control Division of the Korean Food and Drug Administration before you arrive in the country. You'll also need a letter or a prescription from a doctor.
Russia bans most drugs that are illegal in New Zealand but a doctor's letter is required to confirm the need for any medicine containing codeine.
Other medications that Kiwis can buy over the counter, including cold and flu medication, may also need a prescription.