Being home to over 2,000,000 people, Lisbon is one of Europe's safest cities. However caution should be given when in Rossio Metro station and square, where many questionable characters hang out and offer miscellaneous drugs and substances to tourists at all times of the day (they may literally try to hand these supposed drugs to you as you walk by). The same characters operate in groups and usually wander up the main pedestrianised shopping streets in between Rossio Square and Terreiro do Paço square as well as the bar district.These may even warn you that they are part of the Portugues mafia if you object to the repeated attempts to sell you substances.

When on the Metro it is quite common to come across blind beggars as they ride the train from end to end. They typically do not cover their eyes and although harmless, it can be a confronting experience when they walk by you asking for money. Just be prepared for this.

To avoid being pickpocketed, men should carry wallets in their front pockets and women should hold their bags by their bodies, not their straps, while walking or shopping.  Women should also keep a close eye on their bags while eating in restaurants or using public transport.  Hotel safes should be put to use to store valuables and money, and a photocopy, not the original, of your passport should accompany you when you go out.  Leave the original in the safe.  Carry only small amounts of cash and avoid wearing expensive jewelry and engaging in behaviors that thieves may notice, such as overtipping. 

Air quality is very poor particularly in the hot summer months resembling the smell of diesel fumes. Noise may also be a disturbance to your health with considerable amounts of construction work continuously happening in this high density city. Likewise there is very high levels of traffic noise which tends to be worse if you stay in cheaper accommodation that is sited near main roads and without double glazing or that has lowered prices due to a near by building site. You may also be cofronted with disturbing images such as diseased pigeons. There are train and bus stations that are options to escape these disturbances if you choose a healthier destination. 

 Hospital da Luz is a really good private hospital, and many internationals go there too.