It is fairly easy to make a useful tincture, although difficult to obtain the strength and efficacy of the best commercial products.
Capsules filled from dried and ground olive leaves will have some benefits, although not an extract.
If powdered extract can be purchased this can be placed in capsules for greater strength.
More information on making tinctures
More information on making capsules
While well-made tinctures are more complete extracts, and do not lose the volatile constituents during processing, capsules have advantages for some uses.
Follow this link to find out the best uses of different product forms.
Various experiments demonstrate that it does not kill off the main beneficial gut bacteria such as Lactobacillus Acidophilus, Bulgarus and Caucasus and Bifidobacterium Longum.
There are about 500 different species of bacteria in the gut, some good, some neutral and some bad.
The effect of olive leaf has not been tested on all of them, but it does seem to have an affinity only for pathogens (bad disease-causing ones).
If this were not so, it would upset digestion and cause bloating, constipation or diarrhoea. It is actually effective in treating bloating and diarrhoea caused by bacterial or fungal infections.
Taking probiotics between doses should not damage the probiotics at all. If any adverse changes to the gut are experienced over a course of olive leaf, it would be a good idea to take some quality probiotics afterwards to achieve an optimum balance.
If taken in strong tincture form, it is largely absorbed in the stomach and duodenum and should not cause problems further down the digestive tract.
Brands are continually coming and going and different dosage forms suit different uses so this is a complex question.
The established brands which have been on the market for many years should be a safe bet but for detailed information on what to look for go to the leaves page.
To see a selection of the type of products I suggest go to Favourite Olive Leaf Products
If taking for an acute infection you should start noticing the effect from within a few hours to a few days after you start, depending on the type of infection and how early you started treating it.
If you start dosing a cold as soon as you have a scratchy throat it normally doesn't develop at all and two or three doses are all you need.
This is especially the case with tinctures which are very quick-acting. If you already have a cold it may take 3-4 days before you experience a sudden improvement, although the symptoms are normally kept to a low level during this time. If you are trying to reduce high blood pressure, depending on what is causing it you may notice an effect from within a few hours to a few days after starting.
The vasodilating and diuretic effects start within a few hours but cleaning and softening of arteries takes a few weeks to start bringing about a change. These time-scales are from feedback received, not quantified trials.
Note: If on blood pressure medication first consult your physician before taking the extract.
A good quality extract should start to work within a day, although you may not feel the effects for up to a week.
It is made up of 98 known constituents, some of which are known to cross the blood brain barrier, and others which probably can't.
Hydroxytyrosol, a very powerful antioxidant and important constituent can.
Ethanol can also cross the blood brain barrier so tinctures made with ethanol may be more effective preventatives against infections such as meningitis by carrying active constituents across with them.
It is excellent for maintaining health during bodybuilding training, especially prior to competitions or athletic events.
More under typical uses.
I am not aware of any research, traditional information or reason why it should affect birth control in any way.
There is a range of fillers which may be added to capsules or powders.
Some of these are safe and others are best avoided in the long term. See fillers (excipients) to avoid.