Garlic

Are there any interactions with medications?



Isoniazid (INH, Nydrazid)
Interaction Rating: Major Do not take this combination.

Garlic might reduce how much isoniazid (Nydrazid, INH) the body absorbs. This might decrease how well isoniazid (Nydrazid, INH) works. Don't take garlic if you take isoniazid (Nydrazid, INH).



Medications used for HIV/AIDS (Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs))
Interaction Rating: Major Do not take this combination.

The body breaks down medications used for HIV/AIDS to get rid of them. Garlic can increase how fast the body breaks down some medications for HIV/AIDS. Taking garlic along with some medications used for HIV/AIDS might decrease their effectiveness.

Some of these medications used for HIV/AIDS include nevirapine (Viramune), delavirdine (Rescriptor), and efavirenz (Sustiva).



Saquinavir (Fortovase, Invirase)
Interaction Rating: Major Do not take this combination.

The body breaks down saquinavir (Fortovase, Invirase) to get rid of it. Garlic might increase how quickly the body breaks down saquinavir. Taking garlic along with saquinavir (Fortovase, Invirase) might decrease the effectiveness of saquinavir (Fortovase, Invirase).



Birth control pills (Contraceptive drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some birth control pills contain estrogen. The body breaks down the estrogen in birth control pills to get rid of it. Garlic might increase the breakdown of estrogen. Taking garlic along with birth control pills might decrease the effectiveness of birth control pills. If you take birth control pills along with garlic, use an additional form of birth control such as a condom.

Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.



Cyclosporine (Neoral, Sandimmune)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

The affect of garlic preparations on cyclosporine may vary. Some garlic preparations containing allicin might decrease the effectiveness of cyclosporine. However, other garlic preparations containing alliin and alliinase may not. Until more is known about this possible interaction, don't take garlic if you are taking cyclosporine.



Medications changed by the liver (Cytochrome P450 2E1 (CYP2E1) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications are changed and broken down by the liver. Garlic oil might decrease how quickly the liver breaks down some medications. Taking garlic oil along with some medications that are changed by the liver can increase the effects and side effects of your medication. Before taking garlic oil, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include acetaminophen, chlorzoxazone (Parafon Forte), ethanol, theophylline, and drugs used for anesthesia during surgery such as enflurane (Ethrane), halothane (Fluothane), isoflurane (Forane), and methoxyflurane (Penthrane).



Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications are changed and broken down by the liver. Garlic might increase how quickly the liver breaks down some medications. Taking garlic along with some medications that are broken down by the liver can decrease the effectiveness of some medications. Before taking garlic, talk to your healthcare provider if you are taking any medications that are changed by the liver.

Medications that might be affected include certain heart medications called calcium channel blockers (diltiazem, nicardipine, verapamil), cancer drugs (etoposide, paclitaxel, vinblastine, vincristine, vindesine), fungus-fighting drugs (ketoconazole, itraconazole), glucocorticoids, alfentanil (Alfenta), cisapride (Propulsid), fentanyl (Sublimaze), lidocaine (Xylocaine), losartan (Cozaar), midazolam (Versed), and others.



Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Garlic might slow blood clotting. Taking garlic along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.



Warfarin (Coumadin)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Warfarin (Coumadin) is used to slow blood clotting. Garlic might increase the effectiveness of warfarin (Coumadin). Taking garlic along with warfarin (Coumadin) might increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

Dosing considerations for Garlic.

The following doses have been studied in scientific research:

BY MOUTH:
  • For high blood pressure:
    • Garlic extract 600-1200 mg divided and given three times daily.
    • Standardized garlic powder extract containing 1.3% alliin content has been studied for this use.
    • Aged garlic extract 600 mg to 7.2 grams per day has also been used. Aged garlic typically contains only 0.03% alliin.
    • Fresh garlic 4 grams (approximately one clove) once daily has also been used. Fresh garlic typically contains 1% alliin.
  • For prevention of colon, rectal, and stomach cancer: fresh or cooked garlic 3.5-29 grams weekly.
APPLIED TO THE SKIN:
  • For fungal skin infections (ringworm, jock itch, athlete's foot): garlic ingredient ajoene as a 0.4% cream, 0.6% gel, and 1% gel applied twice daily for one week.

Therapeutic Research Faculty copyright

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.