A reader last time wanted to know the recommended guidelines for safe usage of this natural antibiotic. Not too many of you seem to use it, but those who do have given some useful hints. It can be used both internally and externally. One reader wards off tummy bugs while on holiday by diluting a few drops into a 1.5 litre bottle of water, which she sips throughout the day. Shake the bottle well before drinking as the citricidal settles. It can also be used topically, and one reader puts a few drops into her moisturizing cream, or in her shampoo before she washes her hair. It should never be taken neat as it is extremely strong. Another reader does something similar. She puts between four to 12 drops in a glass of water to ward off colds and flu, which takes up to three times a day between meals. She's been taking it for three years and, so far - no colds. Her son took some with him to India, and his stomach problems seemed far less bad than some of his fellow travelers, who ended up queuing up for his citricidal (presumably when not queuing up for the toilet).