Just as with conventional medicines, such as antihistamines or aspirin, many people like to keep a selection of homeopathic remedies on hand for commonplace ailments such as allergies or headaches. Some of the best to have around the house...

Allergy, Watery Eyes: Allium cepa
Dr. Carlston recommends this remedy for allergies when the eyes are watery but not irritated and are accompanied by a burning nasal discharge that worsens in warm rooms and improves outdoors in fresh air.
Allergy, Anxiety, Fatigue: Arsenicum album
This remedy is appropriate for allergies when the eyes and nose are irritated, says Dr. Carlston. Other uses include anxiety and fatigue. A person who is characteristically thin, tense and pessimistic is most likely to benefit from Arsenicum album.
Insomnia: Coffea
A good example of the law of similars, Coffea (coffee) is recommended for insomnia. This remedy is good for people who are physically or mentally overactive and are sensitive to pain or noise.
Anxiety and Depression: Ignatia
Ignatia, or St. Ignatius bean, is for anxiety and depression, especially when related to the death of a loved one or the end of a relationship. This remedy is especially good for people who try to -- but cannot manage to -- control their emotions. A good candidate for Ignatia is a thin, dark-haired, sensitive female.
Headaches Due to Eyestrain or Heat: Natrum muriaticum.
This remedy is for headaches that are aggravated by reading, eyestrain or exposure to the sun and heat. Often, head pain is worse at particular times of the week or month. Natrum muriaticum is also known as sodium chloride, or common table salt, is most appropriate for sensitive, introverted women with a pear-shaped or square build.
Nausea, Vomiting and Allergies, Colds: Nux vomica
Use this remedy for nausea and vomiting after you have overeaten or overindulged in alcohol. Dr. Carlston notes that it also can be taken for allergies or colds accompanied by sneezing, sensitivity to light, chills, irritability and fatigue. Nux vomica is best for driven, impatient, type-A personalities, who are typically lean and tense.
Cough, Cold, Depression, Menstrual Issues, Indigestion: Pulsatilla
Also known as windflower, Pulsatilla is good for colds and coughs, depression, menstrual problems and indigestion experienced after consuming fatty or fried foods. This remedy is most appropriate for very emotional people who need lots of sympathy and attention. A person with a Pulsatilla constitution is most likely to be female, shy, plump and fair-haired.
Muscle Pain: Rhus toxicodendron
Poison ivy! In a highly diluted form as a homeopathic remedy, Rhus toxicodendron is appropriate for people who experience pain, such as arthritis and muscle cramps, which lessens with movement and worsens with resting -- for example, leg cramps in the calf. It is best for those who are sensitive to cold and wet weather.
PMS, Menopause, Candidiasis: Sepia
The principle indications for Sepia are menstrual problems, menopause and candidiasis. Tall, lean, dark women who are irritable at home and happy in company are most likely to benefit from this remedy.
How to Use a Homeopathic Remedy

The remedies I've described here are widely available in conventional pharmacies as well as health-food stores. They come as single- or multiple-ingredient pellets or drops to place under the tongue and are available in various strengths depending on the dilution of the active ingredient. Avoid touching homeopathic remedies, as contact with dirt or oil on skin can potentially inactivate them. It is best to use a spoon.

It's fine to choose any standard over-the-counter (OTC) homeopathic remedy for simple, acute, self-limited complaints, such as coughs or colds, and carefully follow instructions on the label for administration and dosage. Homeopathic remedies are extremely dilute and can often be taken in combination with conventional treatments. However, if you are taking other medications, you should always inform your health-care provider of what you are taking, from homeopathic remedies to vitamins to herbal preparations.