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Garlic contraindications

January 15, 2021
Contraindications and side effects of garlic

The garlic is an ingredient commonly used both in cooking and in traditional medicine. When consumed in moderation, either as part of the diet, as a supplement or natural remedy, garlic is unlikely to cause side effects; even so, it is important to note that its regular or excessive consumption may be contraindicated in some cases.

Read on below for all the details on the subject: possible contraindications , most common adverse effects , interactions, and recommended doses .

Contraindications and side effects of garlic

The most common side effects commonly experienced by people who eat or take garlic every day are bad breath and strong body odor . Although these are annoying symptoms, the truth is that they are harmless to our body1.

But what happens when we eat too much garlic or exceed the dose of a supplement ? It has been seen that excessive consumption of garlic, especially raw garlic, can cause a wide list of side effects2 3 . These include:

  • Gastrointestinal irritation / burning
  • Acidity
  • Sickness
  • Vomiting
  • Diarrhea
  • Flatulence
  • Bleeding (nasal, gums)
  • Burns in the mouth
  • Excessive sweating
  • Headache
  • Allergic symptoms (skin irritation / swelling, hives)

It should be noted that the presence and intensity of these symptoms may vary depending on the amount ingested, the way of consumption, the sensitivity and the health status of each person. Many of them tend to occur when too much raw garlic is consumed on an empty stomach (on an empty stomach).

When used topically, garlic can cause a rash and eczema in some people.

It may interest you: Take Garlic Fasting – Beneficial for Health vs Not Recommended

Who should proceed with caution?

Taking into account that garlic is a vegetable of the Allium family, rich in organosulfur compounds, its excessive use as a medicinal remedy can have negative consequences despite its excellent health properties . Caution is recommended if:

  • You have a sensitive stomach or suffer from any gastrointestinal condition (acute gastritis, acid reflux, ulcer, etc.).
  • You have a liver function disorder . Some studies have reported that excessive consumption of garlic can lead to increased toxicity in the liver4.
  • You have a blood clotting disorder . The compounds in garlic have anticoagulant action, hence they can increase the risk of bleeding. The risk is higher when raw garlic is consumed or if it is combined with medication.
  • You take medication for diabetes . Combining diabetes medications with high doses of garlic can result in too low blood glucose levels.
  • You take medication for high blood pressure or you usually have very low blood pressure. Consuming too much garlic can backfire and cause pressure levels below the normal range5.
  • You are pregnant or breastfeeding . During pregnancy and lactation, women should not exceed the amount of garlic that is normally consumed as part of the diet.
  • You are under medical treatment . Taking garlic supplements or consuming too much garlic in food can interact with different medications.
  • You suffer from pemphigus , an autoimmune skin disease. It is known that garlic , the onion , the leek and other bulbs of the same family may worsen the symptoms of this condition (blisters / sores on the skin and mucous membranes)6.

It may interest you: Garlic in Pregnancy – Is Garlic Good or Bad for Pregnant Women?

When is garlic not safe?

  • People allergic to garlic . People with a known allergy to garlic should avoid consuming it, either as a condiment, remedy or supplement; otherwise they may be in danger of developing a severe allergic reaction (anaphylaxis).
  • People pending surgery or who have recently undergone surgery. Garlic can increase the risk of bleeding in both cases.
  • Babies and very young children . Administration of high doses of garlic in infants and children is considered counterproductive.

Garlic interaction with medications and supplements

Garlic has been observed to interact with the following list of medications 7:

  • Acetaminophen / Tylenol (pain reliever)
  • Contraceptive pills
  • Chlorzoxazone (muscle relaxant)
  • Cyclosporine (immunosuppressant)
  • Theophylline (bronchodilator)
  • Warfarin / Coumadin (anticoagulant)
  • HIV or AIDS drugs
  • Aspirin, Ibuprofen, Naproxen, Diclofenac, and other NSAIDs (non-steroidal anti-inflammatory drugs)

Likewise, it is noted that it is necessary to consult a doctor if you are using a medication to treat any of the following conditions:

  • Infections such as HIV, malaria, or dreamsship
  • Anxiety Depression
  • Asthma, allergies
  • Cancer
  • Erectile dysfunction
  • Heartburn, gastroesophageal reflux disease (GERD)
  • High blood pressure, high cholesterol, or a heart condition
  • Diabetes
  • Migraines
  • Psoriasis, rheumatoid arthritis, or other autoimmune disorders
  • Psychiatric disorder
  • Convulsions

Recommended Reading: Garlic as an Antibiotic – Findings, Benefits, Advantages and Contraindications

It is also recommended to avoid combining garlic supplements with herbal supplements of:

  • Nail
  • Ginger
  • Ginkgo
  • Horse chestnut
  • Red clover
  • Turmeric
  • Danshen
  • Anamú
  • Devil’s claw
  • Willow bark

What is the recommended daily dose of garlic?

There is no single recommended dose. The safe dose of garlic can vary depending on several factors, for example age, health, the way of consumption, among others. However, here is a summary of the most common standard doses according to the garlic product8:

  • Fresh raw garlic . 4 grams (about 1-2 teeth) a day.
  • Aged black garlic . 2-4 teeth a day.
  • Dried garlic in capsules . 300 mg, 2-3 times a day.
  • Standardized extract . 200-400 mg, 3 times a day.
  • Aged extract . 600-7200 mg per day.

Precautions and Warnings About Using Garlic Supplements

  1. Always consult your doctor before taking any garlic supplement, especially if you take medication.
  2. Avoid taking garlic supplements if you are allergic to natural garlic.
  3. Follow the directions provided by the manufacturer on the container label. Do not take more than the recommended dose.
  4. Don’t use different garlic supplements at the same time; this can increase the risk of overdose.
  5. Do not crush or chew enteric-coated garlic pills (special coating to protect the stomach lining).
  6. Stop any garlic supplements for at least 2 weeks before having surgery.

Final thought

Garlic is considered a safe ingredient. Its responsible and moderate consumption does not pose a danger to health in most cases. However, large amounts of garlic in the diet, as well as high doses of garlic supplements, can have consequences.

In the presence of severe symptoms, such as shortness of breath and swelling of the lips, tongue, and throat, discontinue garlic immediately and seek medical attention.

Remember that eating raw garlic in excess is the main cause of contraindications and side effects .



My name is Louise Hammond, and I am the creator of this website, a place to find information about tubers, bulbs and medicinal roots. In I show the properties, benefits, characteristics, photos and images, ways of growing and how to make delicious meals from starchy vegetables.