Is it normal if the face gets all red

Facial redness from a 0.6 mg/h nitroglycerin patch is a known, common effect of the drug itself, not necessarily a sign of danger.

Nitroglycerin works by widening blood vessels. That widening reaches the skin of the face, causing flushing and redness. The evidence here shows this is a predictable effect. In a study of pregnant women using a nitroglycerin patch, 75% got headaches [2], and headache is the same vasodilation mechanism reaching the brain's blood vessels. The same widening that causes the headache also reddens the face. A hand-angiography study found that 16 of 25 patients given intra-arterial nitroglycerin developed facial erythema (redness) [3]. That is a direct measure: the drug dilates facial vessels.

The redness is not a skin allergy in most cases. A true allergic skin reaction at the patch site is possible but rare. One case report describes a woman who developed a spreading rash called erythema multiforme at the patch site, confirmed by biopsy [1]. That rash was itchy, widespread, and lasted days. Simple facial flushing from vasodilation fades when the patch comes off.

The dose matters for how intense the flushing is. A 0.6 mg/h patch is a standard starting dose for angina. The evidence does not test that exact dose for facial redness, but the mechanism is dose-dependent: more drug, more vessel widening, more redness. If the redness is mild and goes away when you remove the patch, it is the drug working. If it is painful, spreading, or accompanied by swelling or blistering, that is a different problem.

My call: facial redness at 0.6 mg/h is a normal drug effect, not an emergency, unless it spreads beyond flushing or includes skin damage. Confidence: high.