What's the right dose?

‘But I’ve already tried evening primrose oil’, patients sometimes say. ‘I took the recommended dose and it didn’t do any good.’
What you’ll find on the bottle of pills or capsules tends to err on the low side for a lot of things. The reason is clear: some people need tiny doses to be effective, and too much may be harmful. On the other hand, people often go away thinking ‘Well, that was no use’, when they simply didn’t take enough, or carry on for long enough.
Evening primrose oil is a good example, because there is a lot of good research into its properties. What we now know is that for some conditions, you need a high dose for the first two or three months: six 500mg capsules daily for rheumatic conditions, four for pre-menstrual tension, and so on. And it doesn’t have unwanted side-effects – except for occasional transient headaches – if you take more than you need. But if you follow the directions on the bottle and take only one or two capsules, you may not get much out of it at all.
Another example is Echinacea, which is now well-known as an immune system booster. You can buy tincture, and the dosage advice is just a few drops daily. That’s fine for long-term protection against colds and so forth, but when you’ve actually got a cold or flu, you need much more than that.
If you buy over the counter, remember that the advice on the bottle is general, and it may not be appropriate for you right now. If you’re not sure, get professional advice. In the long run, it will save you time, money and ill health.