
The number to remember. Throughout Mexico the single emergency number is 911: police, fire and ambulance. It works from any phone, including one with no credit, and there are operators who answer in English. Save it before you leave the hotel.
Other useful numbers. LOCATEL (55 5658 1111) is Mexico City's orientation service: locating people, hospitals, information on official procedures and help when you do not know who to call. For anonymous reporting there is 089. On the highways, the Ángeles Verdes (078) provide free mechanical assistance to tourists. If you are travelling with insurance, note down your policy's assistance number too: it usually resolves a medical question faster than turning up at an emergency room on your own.
Theft, loss and documents. If you lose your passport, the first step is to file a report at the Ministerio Público and then take that document to your embassy or consulate. There is a lost property office for items left on the Metro; for app taxis, the report is made through the app. Keep a digital copy of your passport and visa in your email.
Basic precautions. Use an app taxi or an authorised rank rather than hailing in the street, especially at night. Do not accept help from strangers at cash machines, and prefer those inside banks or shopping centres. Carry only the day's cash. In the tourist areas of the historic centre and Chapultepec there is uniformed tourist police you can approach for help. And keep the exact address of your accommodation written down: colonia names repeat across boroughs.
Health and altitude. The city sits above 2,200 metres: on the first day, go easy on alcohol and physical exertion. Drink bottled or purified water. Pharmacies with an attached doctor's office handle minor complaints cheaply and are all over the city.