An 18-year-old South Australian man has been charged over supplying illegal drugs to three teenagers who, after taking the tablets, were urgently hospitalised.

Police searched the Elizabeth Vale mans home today and found more than 1400 pills marked as Xanax but which actually contained illicit and potentially life threatening substances.

Police say some of the fake Xanax were packaged and ready for supply.

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The man was charged with supplying drugs to a child and trafficking a large commercial quantity of a controlled drug.

He was refused police bail and will appear in the Elizabeth Magistrates Court tomorrow.

SA Police are urging the public to ensure any medication taken is prescribed by a doctor.