The answer will be different depending on where you are going. Air travel within the US shouldn’t be an issue as TSA has about 500 other things they are looking for and dietary supplements that you can buy from OVitaminPro or a health food store are not on their list. If it is liquid you will need to pack it in a checked bag if it is more than 3.4 oz unless you can clear it with TSA. Some medically necessary items like frozen baby formula would be an example of TSA exceptions.
Herbal supplements in capsules, tablets, soft gels or powders (less than 12 oz) have no TSA restrictions. You might be able to take more powder than the 12 oz but put it in a separate bin when going through the checkpoint.
One Way to Organize Vitamins and Supplements
I take a lot of vitamins and supplements so traveling is always a bit of a challenge. I bought plastic bags that are about 2½ inches square. One bag will hold a morning’s or afternoon’s caps and tablets. I then write on the bag, for example Monday a.m. or Tuesday p.m. I put all of these in a larger bag and put them in the suitcase to get checked. I may carry a couple of the small bags with a few supplements like vitamin C and NAC just in case I separated from my bag and want the most important supplements to be with me.
If you only take a few caps or tablets, you might be able to use a commercial pill caddy. I take too many for this to work.
To my knowledge, TSA has no restrictions on vitamins and supplements in checked baggage.
This can be a quagmire. Some countries don’t care about your vitamins and supplements and others do. Do your research the best you can and be careful not to get in trouble for something so simple. In my reading, Thailand comes up as a place to be cautious about what is in your bags. I read things like no more than a 30-day supply and have the vitamins and supplements in their original and sealed containers. Some people report on forums that they travel throughout Asia with their supplements without issue. The information I read is a bit contradictory so choose the method that gives you the most peace of mind.