There was no obvious Chemisty section and I thought this section would generate a more popular feedback.

I have looked on the internet and have found little information.

My question is: How do the head ache 'rollers' such as ''4Head'' work as a replacement for a tablet?

I assumed that the chemical in the roller would still enter the blood steam directly into the area causing the pain, but, I think I am wrong.

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Um, what exactly causes a headache?

Blood pressure may cause it; hormonal changes; tension; a vafiety of things. Many attribute some headaches (there are different kinds) to changes in weather, although I think that's silly.
Yes, often a massage helps, but something more serious than a roller is needed. An Asian woman stopped my mom's migrane by doing a massage, but that included on pulling on my mom's toes and fingers.

I havent explained this well..

4Head is a type of ''roller'' similar in appearence to a anti-persprint that you roll onto your head and it applies some sort of topical treatment which releives the pain of a head ache.
I was wondering how does an external medicine prevent or relieve a head ache?

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Thank you Mr Anonymous.
**Ticks learn something new everyday box**

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