Oral minoxidil is contraindicated in patients with phaeochromocytoma due to the risk of exacerbating this condition.
It should be used with caution or avoided in patients with a history of angina or recent myocardial infarction until the patient is stabilised, as it may worsen cardiac conditions.
In elderly patients, such as a 73-year-old female, the risk of fluid retention, oedema, pericardial disorders, and tachycardia with oral minoxidil is increased, which may limit its use.
Pregnancy is a contraindication, but this is less relevant in a 73-year-old female.
Therefore, the main absolute contraindication is phaeochromocytoma, and relative contraindications include unstable cardiac conditions such as recent myocardial infarction and angina, which are particularly important considerations in older adults.