Educational information, not medical advice — ask your doctor or midwife.
Corazoncillo is the Latin American name for St. John's wort (Hypericum perforatum). It is a small plant with bright yellow flowers. The flowering tops are used as tea, tincture, capsules or a red infused oil.
Most people take it by mouth for low mood. The oil is also rubbed on the skin for minor burns, scrapes and nerve pain.
The short verdict on evidence: for mild to moderate depression the human trial evidence is fair, but it is mixed. For almost every other use it is thin.
This is not a gentle herb. It changes how your body clears many medicines. It can make a drug you depend on stop working.
Long use in a tradition is not proof that a remedy works. It is also not proof that it is safe. Both points apply here.
Two effects matter, and only one of them is firmly proven in people.
In cell studies, hyperforin appears to slow the reuptake of serotonin, dopamine and noradrenaline. These are brain chemicals linked to mood. Whether that fully explains the mood effect in people is not settled.
In people, St. John's wort has been shown to switch on a liver enzyme called CYP3A4. It also boosts a gut pump called P-glycoprotein, which pushes drugs back out of the body.
So many medicines get broken down faster than normal. Their blood levels drop. Sometimes they drop far enough for the drug to fail.
That interaction effect is well documented in human studies. It is not a theory.
It can also add to drugs that raise serotonin. In that case the risk runs the other way, towards too much. This can cause a serious reaction called serotonin syndrome.
Sun sensitivity is a third, smaller effect. In animals and in some human reports, hypericin makes skin react more to bright light.
Standardised capsules and tablets are the form used in most human trials.
Dried flowering tops for tea are common in Latin American markets and herb stalls. The strength of home-made tea is hard to judge.
Alcohol tinctures and liquid extracts are also widely sold.
The red infused oil is for skin use only. Do not swallow it.
Creams and ointments for minor burns and scrapes are sold in some countries. Homeopathic Hypericum is a separate product. It is diluted so far that little or no plant remains.
Corazoncillo reached Latin America with Spanish settlers. The plant itself is native to Europe and western Asia.
European healers used it for wounds, burns and what they called melancholy. The red oil was a classic dressing for cuts.
In Mexican, Andean and Caribbean folk practice it was used for nerves, sadness, cramps and skin sores. Other names include hierba de San Juan and sanjuanera.
Harvest was timed near the feast of St. John in June, which gave the plant its name. Modern research on it began in Germany in the twentieth century.
Call emergency services if you develop agitation, fever, shivering, a fast heartbeat (tachycardia), muscle twitching, stiffness or confusion. These can be signs of serotonin syndrome.
Seek urgent help if your mood gets worse, or if you have thoughts of harming yourself.
Contact a doctor the same week if you feel unusually 'wired', sleepless or over-confident. That can be the start of mania.
See a doctor promptly if you have unexpected bleeding on hormonal contraception, or a severe sunburn-like rash.
If you take any prescription medicine, speak to a pharmacist before you start and before you stop this herb.
In the United States it is sold as a dietary supplement, not an approved medicine. In Germany some extracts are licensed medicines. In the United Kingdom products are sold under traditional herbal registration, and in Ireland oral products are prescription-only.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.
