Customs says it will apologise to a Darwin man who spent three nights in jail for bringing bottles of shampoo and conditioner into Australia.

Neil Parry was arrested last Friday at Darwin Airport after a test allegedly found he had 1.6 kilograms of MDMA, also known as ecstasy, in his toiletries.

His boat and the houses of two of his friends were also searched by police.

Mr Parry was given bail after posting $10,000 surety.

But further testing on Wednesday revealed the substances were just shampoo and conditioner and all charges were dropped yesterday morning.

Customs says it will write to Mr Parry to express its regrets.

Mr Parry says the incident has ruined his reputation and he is considering legal action.