Garlic for Cold

Garlic is one of the most popular home remedies for colds: it is eaten raw, added to dishes, or taken as garlic supplements. We checked what is known about this from research and what risks it carries.

Origin

Garlic is grown worldwide and has been used for a long time in both cooking and folk medicine. The American NCCIH (part of the National Institutes of Health) reminds us that ancient texts from Egypt, Greece, and India describe garlic as a remedy for various ailments, including headaches, pneumonia, and throat diseases.

Today, garlic is mainly sold as a dietary supplement, marketed as immune support, especially during cold and flu season. This is explained by the belief that garlic has antibacterial and antiviral properties. However, the authors of the Cochrane review state directly that these are "attributed" properties of garlic, not proven in treating colds.

What We Know

Label: Weak evidence. The question of whether garlic protects against colds or shortens their duration is essentially answered today by one small study, and independent reviews consider this too little to draw conclusions.

What Studies Say

• Cochrane Review, 2014 (Lissiman, Bhasale, Cohen). The authors searched for studies with random assignment of participants, where garlic was compared to placebo (i.e., a preparation without active substance) or no treatment. Of the eight studies that could fit, only one met the criteria.
• The only study in the review. It involved 146 participants who took either a garlic supplement or placebo for 12 weeks. In the garlic group, 24 colds were recorded, while in the placebo group, there were 65. Overall, participants in the garlic group were sick for 111 days, and those in the placebo group for 366 days. Once someone caught a cold, recovery took a similar amount of time in both groups (an average of about 4.6 days versus 5.6 days).
• Limitations. Participants self-reported when they had a cold. In conclusion, the Cochrane authors state that there is too little evidence from clinical studies; one study suggests a possible preventive effect, but it needs confirmation, and claims about garlic's effectiveness are mainly based on low-quality studies. Adverse effects reported in this study included rash and odor.
• Systematic review from 2022 (Crawford et al.). The authors evaluated supplements marketed as immune boosters, including garlic. According to the NCCIH summary, they found only two studies suggesting a possible benefit of garlic, both involving a small number of participants and with methodological flaws.
• NHS. The British health service states on its cold page that there is little evidence that supplements like vitamin C, echinacea, or garlic prevent colds or speed up recovery.

Safety

Risks

• According to the NCCIH, garlic eaten or taken orally has been used safely in studies lasting up to 7 years. The most common side effects are unpleasant breath and body odor, stomach pain, bloating, and nausea.
• Some individuals have allergic reactions to garlic.
• Garlic supplements may increase the risk of bleeding.
• Fresh, raw garlic applied to the skin can cause severe irritation and chemical burns. A 2021 case review (Hitl et al.) collected 32 publications about 39 patients. Most commonly, these were second-degree burns, sometimes with tissue necrosis, and most often affected the legs. The authors recommend not applying fresh garlic to the skin or mucous membranes.

Who Should Avoid It

• Individuals taking anticoagulants, aspirin, or other medications affecting coagulation should not start garlic supplements without consulting a doctor.
• Individuals before planned surgery or procedures: the NCCIH emphasizes that you should inform your doctor about taking garlic supplements.
• Pregnant and breastfeeding women: according to the NCCIH, garlic in amounts greater than those in regular food may not be safe for them, and little is known about its topical use during this time.
• Individuals allergic to garlic.

Drug Interactions

• Anticoagulants and aspirin: garlic may increase the tendency to bleed. The NCCIH advises talking to your doctor before taking garlic or other herbs if you are on such medications.
• Saquinavir (a drug used to treat HIV infection): in a 2002 study involving 10 healthy volunteers, garlic supplements reduced the amount of this drug in the blood by about half. The authors recommend caution when combining these preparations.
• If you are taking any medications regularly, ask your pharmacist or doctor if you can combine them with garlic supplements.

When to See a Doctor

The NHS states that with a cold, improvement usually comes after about 1–2 weeks. You should see a doctor if:

• a high fever lasts more than 3 days,
• cold symptoms worsen,
• the temperature is very high or you feel hot, cold, or have chills,
• you have difficulty breathing or chest pain,
• you are concerned about symptoms in a child,
• symptoms do not go away after 10 days,
• cough lasts longer than 3 weeks,
• you have a chronic illness (e.g., diabetes, heart, lung, or kidney disease) or a weakened immune system, such as during chemotherapy.

Sources

Compiled by the editorial team of informacja.com based on sources. Status as of October 24, 2026. This is not medical advice.