Michael Petersen, a Royal Australian Air Force veteran, kissed and hugged his wife Linda upon his release on Wednesday.

Looking relieved and emotional after spending five days behind bars, Mr Petersen said he wanted to "spend some time with my lovely wife for a late birthday".

Mr Petersen, 47, had travelled to Bali with his wife for a short holiday to celebrate her birthday.

He declared to Customs that he had dexamfetamine sulfate tablets when he arrived at Denpasar Airport last Friday on a Jetstar flight.

But he was detained because he didn't have a doctor's note or prescription for the drug. He was unaware he needed these.

After his release, he urged others to check the federal government's Smart Traveller website for advice before travelling.

"I normally do. This is the first time I haven't," he said.

The Smart Traveller website warns that some medications, including drugs for attention deficit hyperactivity disorder (ADHD), are illegal in Indonesia.

"Harsh penalties can apply even if you have a prescription. Make sure your medication is legal in Indonesia," it said.

Mr Petersen was carrying 87 pills of dexamfetamine sulfate, which he uses to treat myasthenia gravis - an autoimmune disease that causes severe muscle weakness and fatigue.

These drugs are a stimulant and type of amphetamine and can be used to treat ADHD.

Indonesia classes amphetamines as a type-one narcotic.

Possession of more than five grams of such drugs can lead to severe penalties, including long jail sentences and the death penalty.

While being detained, his wife Linda was allowed to visit him and share a birthday cake. He was also allowed to give her a birthday present - a ring that he had brought with him from Australia.

Copies of his prescriptions, a doctor's note and medical records were sent from Australia to Bali on Sunday.

While in custody, he was taken to a police hospital so a doctor could verify his story.