St. John's wort is a happy plant. Just looking at its yellow, star-shaped flowers is enough to lift my spirits. But in the winter of 1998, I reached for this weedy perennial for more than its aesthetic qualities. Knowing the herb is a proven antidepressant as well as a potential treatment for a variety of ailments, I supplemented with St. John's wort capsules four times a day to shake my winter doldrums.

Optimistic and energetic by nature, I typically work 12-hour days at my computer, walk daily in and around my six-acre herbal vineyard, and travel the world to forage for plants or talk about them. One of my associates jokes that she hardly has the energy to keep up with me, even though her years tally far fewer than my 70.

Thankfully, I have never suffered from debilitating, down-and-out depression. But every fall, as the daylight hours wane, my mood fades too. I lose my usual enthusiasm. I feel out of sorts.

Looking back, I think I've always been less motivated in fall and winter. As a boy living in the South, where sunlight is plentiful, at least in summer, this was not a problem for me. As an adult living in Maryland, farther from the equator, my annual dose of sun is not as potent. And I sense the subtle effects.

In recent years, science has given a name to this common human experience: seasonal affective disorder, or SAD. While it is a form of depression--affecting 10 million people in the United States, the National Institute of Mental Health reports--it usually is mild and short lived. When there is less daytime, our brains don't get as much light by way of our eyes. That translates into fewer nourishing neurochemicals that fuel our sense of well-being.

Annual jaunts to Peru and other South American climes are my favorite antidote for the winter blues. But in 1998, I had no trip planned. So, instead, I took standardized hypericum capsules for the first time. After all, years of research and conversations with colleagues and friends had convinced me hypericum was not to be ignored. Now, I consider it part of my herbal arsenal, a kind of vacation in a bottle, when a trip to the Amazon is out of the question.

Schulz, Hansel, and Tyler suggest that Paracelsus, the sixteenth-century Swiss physician and alchemist, knew of hypericum's effectiveness in treating psychiatric conditions and that German poet-physician Justinus Kerner reported its use in mood disorders in the early nineteenth century.

In more recent years, though, the herb was pushed aside in favor of synthetic antidepressants. Then, in the late twentieth century, reports of its usefulness began to pour in once again. Most came from Germany, where the value of herbal medicines has been more readily embraced.

In 1984, Commission E (a German panel of experts roughly equivalent to the U.S. Food and Drug Administration) approved hypericum for relief of mild to moderate depression and anxiety associated with it. As study after study cited its effectiveness, St. John's wort became the leading antidepressant in Germany. There, it outsells even Prozac, the synthetic pill Americans began gobbling up in the late 1980s.

We're slow to catch on in America. Most of the studies showing hypericum's value as an antidepressant have been done abroad. In 1996, the British Medical Journal published an overview of 23 clinical studies, involving more than 1,700 patients. It concluded that hypericum has antidepressant properties, particularly in mild to moderate cases. And it said the herb was more effective than a placebo and just as potent as prescription antidepressants, without their side effects.

I'm almost positive I'm improving my emotional health by keeping St. John's wort on hand and using it when I feel the need.

Oddly, this herb has gained so much attention overseas, Americans often are surprised when I tell them hypericum grows on its own in each of the 50 states. Early colonists likely brought it with them, either intentionally or by accident. Perhaps the tiny seeds hitched a ride on some food or other supply the settlers carried to the New World.

Thanks to our ancestors, you might have your own supply of this wonderful herb just down the road a bit or on your own soil, as I do. Although I never purposely cultivated St. John's wort until I established my Green Farmacy Garden in 1998, I suppose you could say it grew on me. The weed has a mind of its own in my garden, popping up wherever it likes, to heights of one to two feet, or three feet in an organic garden.

My wild-but-welcome St. John's wort includes Hypericum perforatum and Hypericum punctatum, 2 of about 400 species of the plant. My two happen to be among seven I studied in my years with the U.S. Department of Agriculture. All proved rich in at least one major active ingredient, hypericin, the focus of many studies.

Each year, around the third week of June, my plants bloom on schedule and continue to flower sporadically through first frost. (They may lapse into quiescence during droughts, only to liven up after the rains return.) It's as if they know I expect them. Their yellow petals are speckled with orange and reddish dots that ooze a purplish oil when pinched. Some herbalists liken the dots--where the active ingredients reside--to the pores of St. John's skin. When the flowers are steeped in oil, the "blood" in the pores moves into the oil. My Hypericum punctatum seems to have more of the purplish compounds. Just crushing it stains my fingers.

Sometimes, on summer strolls around my home, I gather the plants' flowering tops--so rich in phytochemicals. I could use them to make my own extract but generally prefer to take standardized capsules. That way, I know I'm getting the same amount of active ingredients with every dose--something I can't be sure of with the plants. Just like humans, each one of them is chemically unique.

St. John's wort also makes a beautiful bouquet. You probably can find the plants in summer at your local greenhouse. Although these commercially grown plants won't be as medicinally active, all St. John's wort seems to contain an aromatic called cineole. In studies, large quantities of cineole enabled rats to zip through a maze more rapidly, whether the compound was inhaled, applied to their skins, or force-fed to them.

Maybe a mere whiff of these mildly scented blooms can help us get happy. Why not place a pretty bouquet on a dining table or nightstand?

St. John's wort contains dozens of active ingredients, such as hypericin, pseudohypericin, protohypericin, and hyperforin. Throughout history, myriad external and internal uses have been reported. Here are the ones I believe are the most scientifically sound:

Burns, cuts, and other wounds. Modern science backs up some of the folklore surrounding hypericum, including its ability to promote healing on our skin, not just underneath it.

Commission E has approved the topical use of St. John's wort oil for primary and secondary blunt and sharp injuries and for burns, skin damage caused by heat, caustics, electricity, or radiation. Hypericum is both an anti-inflammatory and antibiotic, which may help prevent infection. One study in Germany showed hypericum ointment speeded healing and lessened the severity of scarring.

Weed says the oil also reduces skin damage from radiation treatments. Women who applied the oil before and after treatments report their skin stayed healthy and flexible, even after dozens of exposures. Some suggest it may quicken healing from sunburn.

Depression. According to the World Health Organization, depression affects 3 to 5 percent of people. It's characterized by flagging mood, lack of interest in normally pleasurable activities, disturbed eating and sleeping patterns, low self-esteem, indecisiveness, irritability, fatigue, and hopelessness.

In recent years, science has begun to shed light on depression--that its causes are environmental and biochemical, and that often it runs in families. We also have a new understanding of how depression occurs: through an imbalance in neurotransmitters, or feel-good chemicals such as serotonin, dopamine, and norepinephrine, which regulate mood.

This newfound knowledge has led to pharmaceuticals that target specific brain chemicals. One class of antidepressants called monoamine-oxidase inhibitors, or MAOIs, help raise the brain's supply of norepinephrine and dopamine. A newer class, selective serotonin reuptake inhibitors, or SSRIs, such as Prozac and Zoloft, ensure an abundance of serotonin.

While studies show these Food and Drug Administration (FDA) approved drugs are effective for many, there is a price to pay--not only in dollars at the pharmacy but in side effects including dizziness, fatigue, dry mouth, constipation, and sexual dysfunction. Further, people taking the MAOIs must avoid certain foods and medications that interact with the drugs.

In the United States, Prozac is the best-selling antidepressant. But in Germany, about 200,000 prescriptions a month are filled for just one brand of St. John's wort, compared to about 30,000 a month for Prozac, says Varro E. Tyler, Ph.D., Sc.D., professor emeritus of pharmacognosy at Purdue University.

In German studies involving 3,250 people, 80 percent found partial or complete freedom from depressive symptoms, Dr. Tyler says in "The Honest Herbalist--The Secrets of Saint-John's-Wort," published in Prevention magazine.

In the United States, researchers are only beginning to study the herb's medicinal value. A three-year National Institute of Mental Health study at Duke University in North Carolina is comparing St. John's wort with Zoloft, or sertraline, the silver bullet in pharmaceutical treatment of depression in this country. I am, like many, eager to see the results. These university trials satisfy something I have been urging for a decade: that new studies on pharmaceuticals compare them not only with placebo but also with a more promising herbal alternative. I'd like to see the FDA require that for every pharmaceutical so that we can see how the herbal remedy compares with the synthetic drug. But the FDA doesn't oversee herbal products, and there's little financial incentive for big drug manufacturers to test herbs, because they can't patent them. So my plea for mandatory comparisons with herbal alternatives as well as placebo remains unanswered. But the studies at Duke (no relation to myself) are at least one start in the right direction.

You'll most often see hypericin touted on St. John's wort product labels in the United States. But look for hyperforin, too. In Germany, newer studies are focusing on that chemical's action in the treatment of depression.

Herpes. St. John's wort may have antiviral benefits when applied topically to the oozing, painful blisters of genital herpes. The contagious viral infection affects about 45 million Americans, according to the National Institute of Allergy and Infectious Diseases (NIAID).

Herpes simplex II typically causes genital herpes, which is spread mainly through sexual contact with someone who has the virus. It lies dormant in the body between outbreaks. While oral and topical treatments can help reduce the number of outbreaks and their severity, there is no cure.

St. John's wort contains proven antivirals that can help speed healing when applied topically. It also can help heal cold sores and fever blisters caused by herpes simplex I, as well as the blisters of its cousins, chickenpox and shingles (varicella-zoster).

Shingles afflicts about 20 percent of adults who suffered a nasty, itchy bout of chickenpox in their earlier years. It is most common in people over 50. This virus, too, hides out in the body. When it erupts--often as the result of illness or stress--it causes pain and a blistering rash. The pain may linger for years after the visible sores have healed.

Hypericum contains analgesic properties that may help to quell the pain. If I had shingles, I would add a bit of capsaicin topically to my St. John's wort--but only after any open sores had healed.

Studies in the early 1990s showed hypericin is active against herpes simplex I and II. Herbalist Susun Weed also believes hypericum's antiviral powers pass through the skin and into the nerve endings, preventing and checking a variety of problems. She suggests hypericum internally (25 drops tincture) and externally, maybe every four hours, for shingles, cold sores, and genital herpes.

HIV/AIDS. The NIAID says as many as 900,000 Americans may be infected with human immunodeficiency virus, or HIV. It's the virus that causes AIDS, a major worldwide epidemic, first reported in the United States in 1981.

The virus kills or cripples the immune system's T-cells--the good guys--and leaves its victims unable to fight infection and certain cancers. They become susceptible to opportunistic infections, such as cytomegalovirus and herpes. In healthy people, the microbes that carry such infections don't usually cause illness. For people with HIV, they can be deadly.

HIV is passed along most commonly by sexual contact with an infected partner. The sharing of needles and syringes or contact with infected blood also can spread it. Mothers can transmit the virus to their babies during pregnancy or birth, NIAID says.

Some people have flu-like fever, headache, and fatigue a month or two after exposure. Severe symptoms may not occur for a decade or more. As the immune system weakens, signs such as swollen glands and weight loss begin to show. In advanced stages, HIV is categorized as AIDS. The virus can be detected by blood tests.

Standard treatments for HIV/AIDS include drugs such as AZT that interrupt an early stage of virus replication, slowing the virus in the body and delaying the onset of infections. Other drugs called protease inhibitors, such as saquinivir, interrupt the virus at later stages. Because HIV can become resistant to the drugs, often they are used in costly combinations, or drug "cocktails."

These cocktails can run as high as $18,000 a year. They require extreme diligence on the part of the patient, and they are not without side effects--nausea, diarrhea, and gastrointestinal disturbances among them. Patients must also be alert to signs of interaction with other drugs that can result in serious side effects, the NIAID acknowledges.

I first became curious about its role against HIV in the early 1980s. Gordon Cragg, Ph.D., at the Natural Products Branch of the National Cancer Institute (NCI), called and asked where we might be able to find hypericin. "In my garden," I told him. But it was September, past the plant's flowering season.

Daniel Meruelo, Ph.D., professor of pathology at New York University School of Medicine, wanted to examine the potential antiretroviral activities of hypericin in clinical trials. The AIDS connection was new to me, and exciting. The following spring I was able to supply them with hypericum.

Dr. Meruelo was looking at hypericin in test tube studies, especially when combined with ultraviolet light. As with certain cancer treatments, researchers direct the tiny flashlight-like rays to hot spots where the virus is.

Dr. Cragg says hypericin itself did not appear to be the silver bullet in the NCI AIDS screen, but the work continues. Hypericum contains many ingredients that may help slow HIV. Dennis V.C. Awang, of the American Botanical Council Advisory board, has noted that pseudohypericin can reduce the spread of HIV, at least in the test tube. At my urging, Jerry Cott, Ph.D., of NIMH may look at Hypericum hypericoides, yet another species. Hypericum also shows promise in fending off opportunistic infections, such as cytomegalovirus.

Hypericum might be doubly useful in treating AIDS because of its antiviral and antidepressant properties, says a 1995 article in the Psychiatric Times. The Journal of the American Medical Association reports that half of all people with a medical illness also are depressed. Adding St. John's wort to the HIV/AIDS weaponry might boost patient morale and the immune system, possibly slowing the virus.

Many more studies are needed before we know if hypericum can thwart HIV. It is not a cure. Unfortunately, "combination therapies" don't compare pharmaceuticals and St. John's wort for HIV, nor do any of the studies I have reviewed. But, if I had AIDS, I would certainly make the herb part of my daily routine along with antioxidants and immunostimulants to boost my immune system.

St. John's wort generally is available in capsules, tinctures, teas, and in bulk. For therapeutic use, I recommend standardized formulas. In general, follow the directions on the label. Here are some other guidelines, based on my experience:

You may have seen over-the-counter hypericum supplements combined with kava kava, ginkgo biloba, and other herbal remedies. Do they work? There aren't any studies proving they do, but I don't think it's harmful to try them.

Exercise. Exercise and good nutrition go a long way toward balancing our moods. Andrew Weil, M.D., author of several books and the newsletter Self Healing, says aerobic exercise performed vigorously and often "is the best antidepressant." It increases production of endorphins, more of those mood-enhancing neurochemicals.

As a complement to hypericum and exercise, Dr. Weil recommends a few nutrients. Try 1,500 milligrams DL-phenylalanine (less if you have high blood pressure), 500 milligrams vitamin C, and 100 milligrams vitamin B₆ in the morning with fruit or juice about 45 minutes before breakfast. In the evening, add another 500 milligrams vitamin C and 100 milligrams B₆.

Light therapy. Sufferers of depression­­and SAD, in particular­­might also get relief by adding light therapy. Studies show a walk in daylight or regular sessions in front of a specially designed light box may increase levels of serotonin, norepinephrine, and other neurotransmitters that regulate mood. Watch out, though, for signs of photosensitivity.

Mood-enhancing teas. Making teas is a wonderful way to create your own designer herbs, one of my favorites for mood enhancement. For depression, Chris Hobbs, herbalist and author, suggests a tea of St. John's wort, damiana, lavender, rosemary, and wild oats. If I had HIV/AIDS, I'd try my All-Saints-Tea, combining any species of hypericum you can find and self-heal (Prunella vulgaris), sweetened with licorice.

Caution: Contraindications, Interactions, and Side Effects

St. John's wort is thoroughly safe for most users, but even so, certain people would do well to avoid combining it with some substances and to take precautions against possible side effects.