Has anyone experienced nausea, flu like symptoms and/or utter fatigue?

@whidbey I think you have plenty of company when you write that you experience problems at high elevations!! "Normal" people, HCM/HOCM people, Camzyos people, ICD people, dehydrated people, young people, old people, too much coffee drinking, not enough coffee drinking, in-shape people, couch potatoes ... our differences mean that such an uncomfortable state will vary among us if it happens. Sometimes an abrupt change from near sea level to 7,000 ft without time to get acclimatized make people uncomfortable, too. You noted in another post that you have HOCM and are taking Camzyos, so it's a very good question to ask your doctor, the person who knows your physical status and how high altitude may affect you in particular.

Acute Mountain Sickness (AMS): At altitudes like 7000 ft, reduced oxygen triggers symptoms within hours to a day: headache (often), nausea/vomiting, fatigue/lethargy, dizziness, loss of appetite, and malaise. It feels very "flu-like." Many people without heart issues get this; it’s more pronounced if you ascended quickly.

HCM interaction: Your thickened heart muscle already limits efficient blood flow and oxygen delivery under stress. Hypoxia at altitude forces the heart to work harder (higher heart rate, increased strain), which can amplify fatigue, shortness of breath, and even nausea (via reduced brain perfusion or related dizziness). Dehydration, common at altitude, worsens everything.