Hello there VowelLady
I can't advise on the pill formats, but I do have some concern about your relative feeling poorly and throwing supplements at it.
If you feel vitamins could be a problem, it would be better for to
check her blood levels on at least some things,
before starting supplements. Once she starts the supplements, they might mask mild deficiency states. Some deficiencies are important to detect because the reasons need to be ascertained, and the sooner the better.
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I might request a
CBC,
electrolyte panel, plus tests for
vitamin B12,
folate and
iron. Not a bad idea to throw in a vitamin D level but only for reference -- unlikely that would cause her to be "sickly".
After the labs are taken, she could still go ahead and take supplements. Some things are safe enough to take, and we simply might not get enough in the diet.
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Btw, giving a full multivitamin is not necessarily a good thing. If you must give a multivitamin, pick one that has lower levels of Vitamin A (stay away from the 10,000 IU dosages). Excessive Vitamin A builds up and becomes toxic.
Iron is another iffy supplement. Many people think, oh, tired... take iron. XXX! That is true only for people who tend to run low on iron, but the only way to know if that's the case is with a blood test. Getting
excessive iron is not ok -- it causes fatigue etc, symptoms similar to low iron.

I am one whose iron values go over the top if I so much as walk past a supplement containing iron. Unfortunately most multivits and minerals geared at women do contain iron... just something to keep in mind.
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Zinc and B6 are important for immune function and nervous function. Modest doses (up to 100% Daily Intake) of these can be taken safely. Best to take a B complex since the B's all work together, but again, I'd get levels drawn first. These along with Vitamin C (and E in modest doses) might help her if she is getting sick frequently.
Magnesium is something she could take safely if she stepped it up slowly; it might prove helpful especially if she is having problems sleeping which could, in turn, affect her general health. Magnesium blood levels are uninformative because the body leeches magnesium from bone if we don't get enough from the diet.
waves