Dial 106 nationwide for emergencies (police, ambulance, and fire), although you will not necessarily get an English-speaking operator on the other end. The police are generally helpful in emergencies.
The United States reopened its embassy in Havana in 2015, which meand that officials will respond to emergencies involving U.S. citizens, whether or not they have legally traveled to Cuba.
All but the smallest hotels have their own nurses and doctors, who have access to medicines you won't find in most pharmacies or hospitals. Travelers who stay in casas particulares (private houses with rooms to rent) can head for 24-hour clínicas internacionales (international clinics), which have well-stocked pharmacies, or contact Asistur, which specializes in helping tourists in trouble. Its staff can handle anything from insurance claims and lost luggage to repatriation of the deceased. A visit with a doctor at a clinic costs about CUC$25; house calls can sometimes be made for an extra CUC$25. Traveler's insurance is available through Asistur, which can also help you with sorting out various medical, financial, legal, and other problems.
The Clínica Central Cira García, just across the Río Almendares and in a district near Miramar, is dedicated to medical care for foreigners. Considered the best hospital in Havana, the clinic handles emergencies expertly and pleasantly and expects payment in convertible pesos (CUC). Servimed Internacional, part of the Clínica Cira García, is the pharmacy to use; it's open 24 hours a day.
Asistur. Paseo Martí/Prado 212, 7866–4499; www.asistur.cu.
Clínica Central Cira García. Calle 20, No. 4101, Playa, Havana, 7204–2811; www.cirag.cu.
United States Embassy. 7839–4100; havana.usembassy.gov.