The most common effect from oral magnesium even with chelates is a laxative action.
Magnesium does also reduce blood pressure.
Was that dose the total weight of one capsule? Or the elemental
magnesium weight? I suspect it was the total weight. Because 3 capsules are the recommended dose. So the amount of magnesium you consumed is quite small actually. Probably 30mg or so.
I will warn you about your ACE inhibitor. I am just recovering from a SEVERE reaction to lisinopril...which took 10 yrs to manifest. ACE inhibitors increase bradykinin in the body, which has to be metabolized away. This is very common in the lungs...hence your shortness of breath, may be a bradykinin reaction. I got drug induced lupus, from that drug, in addition to bradykinin elevation and terrible pain/burning all over. I couldn't hold my breath either. I was throbbing all over, and was very weak, and had joint pain.
The ACE inhibitors result from research into a S.American viper snake venom which paralyzes prey with elevated bradykinin, putting them into shock. So Merck designed a blood pressure drug based on this work from the 1930's. Snake venom... POISON. As soon as I recover from this, I will probably get tested for hereditary angioedema...which can be triggered also by ACE inhibitors. This will involve an immunologist in about 6mons.
With two BP drugs in your cocktail, you should not have a BP of 160/106. This suggests to me you had a stress reaction, cortisol was dumped and your BP went up. I went off my lisinopril which was causing MORE elevations for me because of my reactions to it. Now I am on a very low dose of beta blocker, and my BPs are 130/80 or less each day (I keep a log).
I have to say, each day now (it has been a month) without that ACE inhibitor and I feel 10 yrs younger and so much better! That reaction was brewing a LONG time.
Here is a wiki on bradykinin:
http://en.wikipedia.org/wiki/Bradykinin
People vary in the reactions to ACE drugs, and if you are simmering with one like I was, you can really really suffer.
I'd search more on bradykinin, if I were you. It is a very potent biogenic amine, and can affect the whole body!
Once armed with your information, I'd get off the ACE drug ASAP, with your doctor's supervision.
Some of us on PN have been using topical lotion magnesium with very good success. I can't tolerate the oral, as it upsets my bowel functions too much, and unreliably.