What most people call an allergy is really an unpleasant digestive complaint; an allergy is when your body actually reacts upon the food and creates such a huge immune reaction that antibodies and other chemicals released to defend against the food actually are destructive to our bodies. Chocolate is not on the list of foods that Americans seem to develop allergies to: milk, fish, eggs, wheat, tree nuts, peanuts, soybeans and shellfish are.
No one has yet proven that acne is related to eating chocolate. Period. Even large amounts of chocolate. So there goes that myth. As far as chocolate being addictive, same thing, there is no clinical evidences to support physical addiction to chocolate. In my opinion, people use the word 'addiction' too loosely these days.
For example, I love chocolate, and I know that it contains substances that release endorphins which make me feel good. I am normal, I like to feel good. But my body tells me when enough is enough. I am not compelled to gorge although I like the taste and how it feels melting in my mouth.
There is no physiological dependency or compulsion. And it's not just me, this is true of all chocolate lovers. There is no real "chocaholic". A 'need' is psychological, an addiction is physical.
Headaches, including migraines, can be triggered by constriction of the blood vessels, and there are two substances in chocolate that can constrict blood vessels, caffeine and phenylethylamine. First of all, buy pure chocolate that does not contain these ingredients added to it.
Then experiment. Drink coffee or soda that contains caffeine but not phenlyethylamine, and see if you get a headache. Or visit a doctor and have some blood tests done to determine what food or ingredient triggers your headaches. Chances are, you can buy chocolate without that particular ingredient.
Food sensitivities can trigger symptoms of allergies and asthma, but rarely is chocolate one of these. Most likely, there is some additive or contamination with another food product that is causing the problem. For example, much of the chocolate consumed is milk chocolate, and milk products could be the cause of the symptoms.
So read your labels and eat gourmet dark chocolate, it's a healthy treat in moderation, containing antioxidants and cocoa phenols that can lower blood pressure.