The side effects of long-term garlic supplementation are largely unknown. Possible side effects include gastrointestinal discomfort, sweating, dizziness, allergic reactions, bleeding, and menstrual irregularities.

Effect of Garlic

Diabetes: Garlic can lower blood sugar. In theory, taking garlic might make blood sugar too low in people with diabetes.

Stomach or digestion problems: Garlic can irritate the gastrointestinal (GI) tract. Use with caution if you have stomach or digestion problems.

Low blood pressure: Garlic can lower blood pressure. In theory, taking garlic might make blood pressure become too low in people with low blood pressure.

Several reports of serious burns resulting from garlic being applied topically for various purposes, including naturopathic uses and acne treatment, indicate care must be taken for these uses, usually testing a small area of skin using a low concentration of garlic

Some breastfeeding mothers have found, after consuming garlic, that their babies can be slow to feed, and have noted a garlic odor coming from them.

Surgery: Garlic might prolong bleeding and interfere with blood pressure. Garlic might also lower blood sugar levels. Stop taking garlic at least two weeks before a scheduled surgery.

If higher-than-recommended doses of garlic are taken with anticoagulant medications, this can lead to a higher risk of bleeding from the blood it travels to the lungs (and from there to the mouth, causing bad breath; see garlic breath) and skin, where it is exuded through skin pores. Washing the skin with soap is only a partial and imperfect solution to the smell. Studies have shown sipping milk at the same time as consuming garlic can significantly neutralize bad breath. Mixing garlic with milk in the mouth before swallowing reduced the odor better than drinking milk afterward.


If consumed in reasonable quantities, ginger has few negative side effects. It is on the FDA's "generally recognized as safe" list, though it does interact with some medications, including the anticoagulant drug warfarin and the cardiovascular drug nifedipine.

The United States Food and Drug Administration warns that consumption of aristolochic acid-containing products is associated with "permanent kidney damage, sometimes resulting in kidney failure that has required kidney dialysis or kidney transplantation. In addition, some patients have developed certain types of cancers, most often occurring in the urinary tract

Side effects of ginger include:

increased bleeding tendency

abdominal discomfort

cardiac arrhythmias (if overdosed)

central nervous system depression (if overdosed)

dermatitis (with topical use)



mouth or throat irritation.

What Are Warnings and Precautions for Ginger?

Ginger may cause hypersensitivity and gallbladder disease.

This medication contains ginger. Do not take African ginger, black ginger, cochin ginger, imber, Jamaica ginger, race ginger, rhizoma zingerberis, rhizome, sheng jiang, shokyo, zingibain, zingiber officinale, or zingiberis, if you are allergic to ginger or any ingredients contained in this drug.

Allergic reactions to ginger generally result in a rash.Although generally recognized as safe, ginger can cause heartburn and other side effects, particularly if taken in powdered form. It may adversely affect individuals with gallstones, and may interfere with the effects of anticoagulants, such as warfarin or aspirin.

Evidence that ginger helps alleviate nausea and vomiting resulting from chemotherapy or pregnancy is inconsistent. 

There is no clear evidence of harm from taking ginger during pregnancy, but its safety is undefined. Ginger is not effective for treating dysmenorrhea. There is weak evidence for it having an antiinflammatory effect, but insufficient evidence for it affecting pain in osteoarthritis.