Customs regulations
Each non-muslim adult can bring in four items of alcohol , eg four bottles of wine, or four bottles of spirits, or four cases of beer (regardless of alcohol content).
The UAE takes an infamously strict line on medicines, with many common drugs, notably anything with containing codeine, diazepam (Valium) or dextromethorphan (Robitussin) being banned unless you have a notarized and authenticated doctor's prescription. Visitors breaking the rules, even inadvertently, have found themselves deported or jailed. The US Embassy to the UAE maintains an unofficial list [4] of what may not be imported. However, as many people have noticed even when having all the correct documentations in both English and Arabic have not been enough to be able to bring in some medication and have resulted in both refusal of entry into the UAE and in some cases fines or jail time. It is advised not bring any kind of medication with you if you can manage without them.
Don't even think about bringing in narcotics: possession of even trace amounts leads to a minimum of four years in prison. Using Khat/qat (a flowering plant that contains an alkaloid called cathinone) which is popular in other nearby countries (notably Yemen) is also illegal, with life prison sentences possible