Someone posted that both hydroxychloroquine and azithromycin have adverse effects on heart rhythm. But in the case of hydroxychloroquine, it may happen only after a longer period of time than required to treat COVID-19. And in the case of azithromycin, at least one paper suggests the determination is in error. Someone said the problem is atrial fibrillation? I did not see that. I did see concern about "prolonged Q-T interval" on the EKG. This issue, if really present, can cause lethal arrhythmias due to a phenomenon of cardiac conduction called "torsade de pointes" (from the French I suppose) and also ventricular tachycardia and fibrillation. These are very very unlikely in short term use in people who do not have pre-existing heart disease. People who do must consult their cardiologist for advice including how to monitor their heart if they take the drugs.
I will post links when I have more time. Anyway, the issue is a bit moot. There is, as of yet, no persuasive evidence for taking the drugs to prevent COVID-19.
And who said that self-medication is easy?