The following four herbal supplements can usually be purchased at most pharmacies and health food stores. All four can assist in reducing vocal hoarseness and fatigue. None of these will eliminate or fight infection.
If your vocal fatigue or hoarseness is from straining or singing with tension, then ultimately a supportive vocal technique is really the answer and should be learned before you develop long term vocal problems. Straining and tension are the result of how you sing, not what style you sing. In the meantime, here are a few temporary remedies.
Licorice Root Tea: Place several licorice twigs in a saucepan with water. Bring to a boil and then reduce heat to simmer for 20 minutes. Strain the liquid, allow to cool a bit and sip slowly. You may find licorice sweet enough, but if not, sweeten with honey. This reportedly helps with vocal fatigue, hoarseness, and coughing.
Ginger Root Tea: Another remedy for coughing is ginger root tea. While coughing is a natural way you body expels mucous, it can be very rough on your vocal folds. Buy a piece of ginger root in your grocery store, slice it thinly and follow the same cooking directions as for licorice root tea. Sip the resulting ginger tea throughout the day and especially at night when coughing can tend to be more severe. This may be more effective for a cough than licorice.
Chewable Papaya Enzyme Tablets: Take a tablet and tuck it between the gums of your upper teeth and cheek. This permits the enzymes to go straight into your system through your membranes instead of your stomach. Let it dissolve without chewing it. You can do this every few hours while the fatigue or hoarseness is severe and then reduce frequency as the condition alleviates.
Bromelain: This enzyme is derived from the stems of pineapples and is usually used as a digestive aid. However, if taken on an empty stomach, it will act as an anti-inflammatory and can reduce swelling in the vocal folds.
Bromelain, Papaya, Licorice and Ginger Root are not antibiotics and will not eliminate an infection.They should help reduce swelling and inflammation. Of course the best remedy for vocal fatigue is to avoid it in the first place by learning and using a good vocal technique and warm-ups.