TL;DR: Spraying minoxidil to mouth is very dangerous and sublingual minoxidil is less effective compared to proper, real oral minoxidil.
Sublingual minoxidil as spraying it to mouth is less effective and far more dangerous than oral minoxidil. Applying a few drops of topical minoxidil to a fluid and drinking it may or not may be less effective (for a few drops to a drinkable solution) but definitely more dangerous than oral minoxidil nevertheless.
In a 5% topical minoxidil liquid solution, a 60 ml bottle contains 3 g of minoxidil. On average, 60 ml gives 300 doses, which means each spray is 60/300 = 0.2 ml.
If 3 g is evenly distributed, then 3/300 = 0.01 g, meaning each spray delivers 10 mg of minoxidil. Around 10 mg and above is the dosage prescribed for hypertension patients.
Someone who sprays 2–3 pumps into their mouth ends up taking 10 × [(2+3)/2] = an average of 25 mg, which means they could literally have a cardiac event, even die — and there are plenty of people on Reddit who have drunk this and reported heart palpitations, etc.
The same applies to foam. In 5% foam, 100 g contains 5 g of minoxidil. If each pump produces around 0.5 g of foam, then 0.5x = 100 → x = 200.
5 g / 200 = 0.025 g = 25 mg of minoxidil per pump.
If each pump was 0.25 g, then it would be 12.5 mg — which is also a blood-pressure-medication-level dose.
As a real world example, the famous Rogaine® foam is 60 g, meant to be used as 30 × 2 applications. If someone uses 1 g per day twice and does 5 pumps, that makes 0.2 g per pump.
60 / 0.2 = 300 doses.
With 57 g (other ingredients) + 3 g minoxidil, 60 g / 300 and 3 g / 300 = 0.01 g, meaning 10 mg per pump — which again is a blood-pressure-medication-level dose.
Concentrations below 5% are generally weak; anything above it — for example 7% — already contains more, and will exceed 10 mg per dose, which is at or above the starting dosage range given to hypertension patients.
One or two drops of topical minoxidil (1 ml is assumed roughly equivalent to 20 drops) it may be in range of 2.5mg-5mg, which is generally safe, HOWEVER, you canNOT for sure know the dosage. Keep in mind that typically a 5% topical solution has 50mg of minoxidil content per every 1 ML if it is truly homogenous and also keep in mind that sublingual minoxidil is NOT metabolized by liver if it enters blood stream immediatly, applying a few drops of 5% topical minoxidil eg. 1-2 drops to a 100ml drinkable solution and drinking it may be different but am NOT sure. Get proper oral minoxidil eg. Loniten® instead of this shit for your health.
edit:fixed the wording and grammar, added registered brand symbols.
. natural selection.