10 Facts About Garlic Dosage For UTI

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Using garlic to treat UTI is not a novel idea, but what is the right garlic dosage for UTI? In this post we will investigate why garlic (Allium sativum) could be useful in UTI treatment, what do we know about why garlic works, how much garlic you should take to supplement your UTI treatment.

#1 Garlic Is An Ancient Remedy

Garlic has been known for its antibacterial properties for ages.

For example, garlic was one of the plants recommended for its antimicrobial properties in Meddygion Myddvai, a 14th-century Welsh manuscript.

You might have heard that we live in the “post-antibiotic era”, which means known antimicrobials are becoming less effective due to the pathogenic bacteria becoming resistant. That’s why researchers are turning to plants to find ideas, inspiration, and new cure for infections like UTI.

In an attempt to validate long-known remedies and to understand their mechanism of action, hundreds of in-vitro (performed in a lab setting) studies have been conducted with garlic extracts. Garlic extracts were also used in many animal models to verify its effectiveness against various bacteria.

There are also plenty of studies that cover the effects of garlic on cholesterol, blood pressure, red blood cells, cancer, and weight loss in human clinical studies. However, I was not able to come across a clinical, human in-vivo study related to UTI (besides a two-case UTI prevention report that I’ll mention later). This does not mean that garlic is useless against UTI, but it definitely means that there is no recommended, clinical evidence-based garlic dosage for UTI as of yet.

#2 Calculating Garlic Dosage For UTI

In studies, time and time again, garlic demonstrates strong antibacterial properties. If you just glance through the results, it easy to feel convinced that garlic could cure a UTI and all other diseases in the world along with it.

However, most of the studies are performed in a lab (in vitro) or on animals, and animal models are different than human experiments. For example, animals are frequently subjected to very high doses or the extract is delivered via injection.

And when it comes to lab studies, bacteria are directly exposed to garlic concentrate on a Petrie dish. This is never the case in humans since garlic juice first needs to be metabolized by the liver before it reaches any other organs. Therefore, while these studies are a great first step to see what potential an herb has in fighting certain bacteria, there is no way to tell how this research can be translated into clinical recommendations for humans.

#3 Garlic Is Antibacterial

When you drink garlic juice or eat raw garlic, the beneficial substances undergo major transformations leading to compounds that were not present in the original product (raw garlic or garlic supplements). These compounds are still not well researched.

For example, you might know that Allicin (diallyl thiosulfinate), derived from garlic, is a highly potent natural antimicrobial substance. In a lab, it inhibits the growth of a variety of microorganisms, among them antibiotic-resistant strains.

But Allicin is not even present in the intact garlic clove, it is only released if you cut or crush garlic since it’s generated by the enzyme alliinase in the course of cell disruption.

Furthermore,  Allicin’s life is rather short. For example, it’s never detected in urine regardless of whether you take raw garlic or garlic pills, which leads us to conclude that Allicin is processed by the body into new compounds.

These compounds include disulfides, trisulfides, dithiins, and ajoenes since this is what is detectable in urine after garlic consumption. These compounds constitute the typical aroma of garlic but may also contribute to its beneficial health effects.

#4 Garlic Is Safe For Good Bacteria And Kidneys

Since I’m always concerned about the wellbeing of my microbiota, I want to know how antibacterial remedies that I take affect it.

Good news (link to  study results): water-based garlic extract significantly “enhanced the growth of one strain of probiotic bacteria (L. reuteri) whilst inhibiting both pathogenic strains of E. coli at a 1:50 dilution.” Obviously, there are thousands of other probiotic strains that we should worry about, but at least we have one data point confirming that garlic-based remedy won’t hurt your own good bacteria.

Read more about why beneficial bacteria are critical in your fight against recurrent UTI.

Some doctors were concerned if consuming garlic might have a detrimental effect on kidney health. On the contrary, a study named “The Beneficial Effects of Allicin in Chronic Kidney Disease Are Comparable to Losartan” established that Allicin showed “antihypertensive, antioxidant, and nephroprotective effects”. Basically, garlic lowers blood pressure and keeps your kidneys healthy.

When comparing the beneficial effects of Allicin to those of losartan: “In fact, the effect of allicin on blood pressure and renal function is comparable to reductions seen with losartan, a prescription drug commonly used as a first-line therapy”, concludes the author. So if you have high blood pressure (perhaps, because of all the UTI-related anxiety), garlic could help to kill two birds with one stone.

Other beneficial effects of garlic mentioned in research papers:

  •  Reduces total cholesterol and Low-density Lipoprotein (LDL-C),
  •  Increasing High-density Lipoprotein (HDL-C).
  •  Provides a variety of anti-cancer properties.

#5 Could Garlic Destroy Bacterial Biofilms?

Probably one of the most important discoveries for chronic UTI sufferers is that garlic can affect bacterial biofilms.

E.coli that causes UTIs is known to form biofilms that enable bacteria to avoid attacks from our own immune systems, resist antibiotics and therefore becoming the source of persistent chronic infections. Fighting a chronic infection without destroying the biofilms is impossible.

Subinhibitory Concentrations of Allicin Decrease Uropathogenic Escherichia coli (UPEC) Biofilm Formation, Adhesion Ability, and Swimming Motility study investigated the effect of Allicin, isolated from garlic essential oil, on pathogenic E.coli, biofilm formation and growth, along with its effect on ability of E.coli to adhere to bladder walls and move around (“motility”).

As the result, it was established that Allicin decreased pathogenic biofilm formation and affected its architecture. Allicin was also capable of dispersing biofilm. Furthermore, allicin decreased the bacterial adhesion ability and swimming motility, which are important for biofilm formation”. Basically, it incapacitates E. coli bacteria and partially disables them.

The study also revealed that the presence of 50 µg/mL allicin decreased the expression of UPEC type 1 fimbriae adhesin gene fimH. This means that E. coli can’t grow their little nasty hands that they use to grab on to your bladder walls and this, in return, allows you to flush the bacteria out.

The major problem though: Allicin as I mentioned above, is not even detectable in urine (regardless of how much garlic you ate). However, let’s hope that after Allicin is metabolized by our body, and the resulting components still carry on similar qualities as their parental compound.

#6 What Is Garlic Dosage For UTI?

As I mentioned earlier, it is hard to know until we actually study garlic dosage for UTI in human clinical research.

However, you are already eating garlic, I assume? Therefore, you might as well try to see if it could boost your preventive or treatment plan. Obviously, if you have been experiencing your symptoms for more than a day and you keep feeling worse, do not experiment with any supplements and seek medical help.

If you are already taking antibiotics, most likely it is OK to supplement with garlic as a way to give your therapy a boost, but make sure to consult with your physician first.

And now, let’s look at what dosages seem to work in other studies and didn’t cause side-effects.

UTI Prevention

  • Most human studies with garlic averaged a dosage in a range of 600-1,200 mg garlic extract, usually divided into multiple doses and taken with or after food.  This seems to be a very safe dosage, and on average comes close to an intake of one supermarket clove (weighs about 4-7 grams). 
  • Only one UTI related human study that references garlic supplementation, mentions that women took 2-6 garlic oil softgels per day along with other supplements to prevent UTI.

UTI Treatment Dosage

  • The garlic dosage for UTI that worked for some seems to be up to 9 garlic cloves a day, split into three equal doses.
  • You can cut garlic into pill size pieces, but I would recommend crushing it as much as possible before swallowing to release potent Allicin. The problem with this dosage is, obviously, that cloves are not a unit of weight.
  • One garlic clove weights anywhere from 4-30 grams. So make sure to use a digital scale to stay under the toxic limits (see below).

#7 How Much Is Too Much?

Garlic can be toxic if consumed in very high doses, so supplementation should never go beyond 5% of the diet (total weight of all the food you eat). Basically, if you ate 5 grams of garlic, make sure you also ate 95 grams of some regular food.

Do not take large doses of garlic when hungry or on empty stomach, it could become more toxic.

This results in the following maximum dosages:

  • 17 grams for a 150 lb person (Approximately 5-7 garlic cloves per dose, if taken with 300-340 grams of food)
  • 22.7 grams for a 200 lb person (Approx. 7-9 garlic cloves)
  • 28.4 grams for a 250 lb person (Approx. 9-11 garlic cloves)

The lowest dose associated with raw garlic toxicity was about of 400mg/kg and resulted in testicular toxicity.

Individual susceptivity to garlic toxins could vary, so don’t go crazy.

#8 How Soon Garlic Should Work?

A research paper named Detection of Volatile Metabolites Derived from Garlic (Allium sativum) in Human Urine highlights three garlic-derived metabolites (AMS, AMSO, and AMSO) that reach their maximum concentration in urine at about 1 h after garlic consumption. Therefore, you can expect some results within an hour or two, but it might take more than one dose.

#9 Other Precautions And Drug Interactions

Garlic interacts with Saquinavir (even in small doses), and with Warfarin (in larger doses). As with any home remedy treatment, consult your physician for any other contradictions.

It is possible to be allergic to garlic supplements if you are allergic to garlic itself.

#10 How To Consume Garlic?


Microwaving garlic will partially destroy the beneficial components of the vegetable, but grilling and roasting will not damage the bioactives, provided the garlic is sliced or crushed beforehand to release Allicin.

Some also make garlic tea. I personally find even the idea of garlic tea repelling. I’d rather eat it crushed with bread, sour cream and salt. Or just swallow crushed garlic fast and eat some bread afterward.


When choosing raw garlic, go for purple colored bulbs (versus white). Purple ones have a higher content of beneficial flavonoids.

Make sure to weight your garlic cloves and don’t just eye the amount of garlic when trying to estimate garlic dosage.

An average garlic clove yields 9 milligrams to 15 milligrams of Allicin when crushed. Most garlic supplements express an amount of Allicin in mcg. Divide by 100 to get milligrams. Divide by 1000 to get grams.


Most garlic supplements are standardized on allicin potential and are enteric-coated to prevent gastric acid inactivation of the allicin-producing enzyme, alliinase.

A study called Low allicin release from garlic supplements: a major problem due to the sensitivities of alliinase activity found out that 83% of 24 known brands of enteric-coated tablets are releasing less than 15% of their potential. “Only when tablets had high alliinase activity and disintegrated rapidly did they show high allicin release.”

Therefore, go with capsules instead.

Have you tried garlic for UTI treatment or prevention supplementation? Please share your experience in the comments below.

To summarize:

  • Raw garlic should not exceed more than 5% of your total food consumption
  • Make sure to use a digital scale to avoid taking too much garlic
  • For supplementation, choose purple garlic over white garlic
  • Garlic has known interactions with certain prescription medications
  •  2-6 garlic oil softgels per day could be taken to supplement your UTI prevention plan
  • The garlic dosage for UTI that worked for some seems to be up to 9 garlic cloves a day, split into three equal doses.

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