I never gave it much thought. But it turns out, I should have.

I take therapeutic niacin in doses between 3-5k a day. The only known issue with this level is with timed release/flush free versions. When my online supplier sent me tablets instead of the capsules I thought I had ordered, I thought it wouldn't make a difference.

But it did.

The tablets acted as a time release version; and I got a bout of hives. Checked with doctor, with pictures and phone calls, because I was worried about shingles, but they are calling it a "unusual stress reaction" and I'm thinking "niacin rash" from timed release.

Tablets break up and get absorbed at different rates. This is bad when people take niacin. It might be a factor in any supplement: something to think about.

More info at this link:

Tablets vs. Capsules: Pros, Cons, and How They Differ