Altitude in Mexico City

What you may notice on arrival

Acute mountain sickness usually occurs above about 2,500 meters, although some healthy people have symptoms from around 2,000 meters. When it occurs, it usually starts 2 to 12 hours after arrival, often during or after the first night. The most common symptoms are:

• Headache, which is the main symptom.
• Tiredness.
• Dizziness.
• Nausea or loss of appetite.

The symptoms feel similar to a hangover and, if you do not go higher, usually improve within 12 to 48 hours.

How to acclimatize

• Take it easy: keep physical activity light during the first 48 hours.
• Alcohol: avoid it during the first 48 hours.
• Coffee: if you drink it daily, do not stop suddenly, to avoid a withdrawal headache.
• Trips to higher places: if you plan to visit nearby mountains or volcanoes, go up gradually and do not go higher to sleep if you have symptoms.

Warning signs

Severe forms of altitude illness are more typical of higher altitudes. Even so, call 911 or go to an emergency room if you or your companion has:

• Confusion, drowsiness, unusual behavior or trouble walking in a straight line.
• Shortness of breath at rest, a persistent cough, chest tightness or blood-tinged sputum.
• A severe headache that gets worse despite rest.
• Persistent vomiting.

Who should see a doctor before traveling

Get a medical assessment before your trip, even if your condition is under control, if you:

• Have heart disease, or had a heart attack or stroke in the past 90 days.
• Have moderate or severe COPD or another chronic lung disease.
• Have severe obstructive sleep apnea.
• Have a high-risk pregnancy, or are pregnant and plan to sleep above about 3,050 m (10,000 ft).
• Have sickle cell disease or sickle cell trait.

Preventive medicines

There are medicines to prevent altitude illness, but only a doctor should prescribe them after reviewing your health, your itinerary and the medicines you already take. For most travelers staying in the city they are not usually needed. Talk to a doctor first if you have had moderate or severe altitude sickness, high-altitude pulmonary or cerebral edema, or plan to sleep above 2,750 m (e.g., volcano huts).

Air quality and environmental alerts

Mexico City has days with poor air quality due to pollutants such as ozone and particulate matter. The city's Environment Department (SEDEMA) publishes the continuously updated AIRE Y SALUD index, the forecast and environmental alerts (contingencia ambiental) at aire.cdmx.gob.mx (in Spanish).

Check the index's recommendations before exercising outdoors, especially during an environmental alert, and follow them.

Frequently asked questions

Sources

1. Hackett PH, Shlim DR. High-Altitude Travel and Altitude Illness. In: CDC Yellow Book 2026: Health Information for International Travel. Centers for Disease Control and Prevention; 2025. cdc.gov
2. Luks AM, Beidleman BA, Freer L, et al. Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update. Wilderness Environ Med. 2024;35(1_suppl):2S-19S. doi:10.1016/j.wem.2023.05.013
3. Omidi A, Hawley GD, Kain D, et al. What Is New in Altitude- and Cold-Related Illnesses of Travel: Appraisal and Summary of the Updated Guidelines from the Wilderness Medical Society. Int J Environ Res Public Health. 2025;22(2):284. PMC11855094
4. Mexico City Environment Department (SEDEMA), Atmospheric Monitoring Office. Air quality: AIRE Y SALUD index and environmental alerts [Spanish]. Accessed October 19, 2026. aire.cdmx.gob.mx
5. Mexico City Government. About Mexico City. Accessed October 19, 2026. mexicocity.cdmx.gob.mx

Written and reviewed by Dr. Cristóbal J. Ortega-Arenas, physician (UNAM), professional license 14848636. Last reviewed: October 20, 2026. General information for adult travelers; it does not replace a medical consultation.