Cloves—those tiny, fragrant buds—are praised for their bold flavor and impressive health benefits.

Known for their antioxidant and anti-inflammatory powers, they’ve been hailed as a super-spice that soothes toothaches, boosts immunity, and spices up your favorite dishes. But behind their pleasant aroma lies a side few talk about: in certain cases, cloves can do more harm than good.

If you regularly sprinkle them into meals, sip clove tea, or apply clove oil, it’s worth knowing the risks. For people with specific health conditions, cloves can shift from healing helper to hidden hazard. Here are nine situations where they may be silently harming you.

1. Acid Reflux or GERD

Cloves contain eugenol, which relaxes muscles—including the lower esophageal sphincter that keeps stomach acid from rising. If it relaxes too much, acid can flow upward, causing heartburn. For the 20% of adults with GERD, cloves may worsen burning, bloating, and regurgitation.

2. Blood Thinners or Bleeding Disorders

Eugenol naturally thins the blood, which can be dangerous for those on anticoagulants like warfarin or with conditions such as hemophilia. Mixing cloves with these drugs increases the risk of bruising, bleeding, or complications during surgery.

3. Spice Allergies

If you’re allergic to spices or plants in the Myrtaceae family (like eucalyptus or allspice), cloves could cause itching, swelling, or even breathing difficulties. Severe cases may lead to anaphylaxis. A patch test before consuming or using clove oil is wise.

4. Pregnancy or Breastfeeding

While small amounts in food are generally safe, high doses or clove oil may stimulate uterine contractions, increasing the risk of preterm labor. Eugenol can also pass into breast milk, possibly affecting infants. Always consult your doctor before use.