Educational information, not medical advice — ask your doctor or midwife.
Ajo is the Spanish word for garlic, the bulb of Allium sativum. It is a kitchen food in almost every country. In Latin American homes it is also kept as a remedy.
People use it for colds, high blood pressure, high cholesterol and stomach worms. It is eaten raw or cooked. It is also sold as tablets, capsules and aged extracts.
Here is the short verdict on the evidence. Trials in people show small but real drops in blood pressure and cholesterol. Most other claims are not proven.
Long use in a tradition is not proof that a remedy works. It is also not proof that it is safe.
Garlic's effects start with sulfur compounds that form when you cut a raw clove. The main one is allicin.
In lab and animal studies, these compounds appear to relax blood vessels. They may raise two gases the body uses to widen vessels, nitric oxide and hydrogen sulfide.
In cell studies, garlic compounds also slow platelets, the blood cells that build clots. This fits reports of easier bleeding in some people who take high doses.
In test tubes, garlic slows the growth of many bacteria and fungi. Whether that happens inside the body at food doses is not established.
The blood pressure effect is the best supported one in people. The drop is modest. It is smaller than what blood pressure medicines achieve.
Garlic is sold both as ordinary food and as a supplement. The common forms are:
Fresh cloves, raw or cooked.
Dried garlic powder tablets, often coated to pass through the stomach.
Aged garlic extract, in capsules or liquid, with far less smell.
Garlic oil softgels.
Home preparations, such as crushed garlic in honey, oil or warm milk.
Odour-free products often hold little allicin. Coated tablets aim to release allicin past the stomach.
Strength is not standard across brands. Check the amount per dose on the label you hold.
Homemade garlic kept in oil is a food safety risk. It must be kept cold and used quickly.
Garlic reached the Americas on Spanish and Portuguese ships in the 1500s. It joined local healing practice quickly and became a household remedy.
Curanderos and home healers used it for coughs, colds, earache and intestinal worms. It was also tied to protection beliefs, such as cloves carried against mal de ojo (the evil eye).
In Mexican, Caribbean and Andean homes it was crushed into honey, oil or warm milk. Older European, North African and Middle Eastern records describe much the same uses.
Stop garlic supplements and get medical advice if you notice any of these:
Unusual bruising, nosebleeds or bleeding gums.
Black or tarry stools, or vomit that looks like coffee grounds.
Severe stomach pain, or heartburn that will not settle.
Blistering or a burn where garlic touched the skin.
Get emergency help for swelling of the lips, tongue or throat, a rash with trouble breathing, or fainting. These can be signs of a severe allergic reaction.
Tell your doctor that you take garlic before any surgery and before starting a new medicine.
Garlic is an ordinary food worldwide. In the United States, garlic supplements are sold as dietary supplements and are not approved by the FDA before sale. In the UK and EU they are sold as food supplements, not as medicines.
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.
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