Spearmint Tea Side Effects + Who Should Avoid It

Key Takeaways

• Short studies provide some reassurance, but do not establish a safe daily amount for everyone
• Small trials found hormone changes in women; effects on male testosterone and fertility remain uncertain
• Spearmint behaves differently from peppermint when it comes to acid reflux
• Some prescription medications may interact with spearmint, always check with your pharmacist
• The studies discussed here cannot establish safety over years of daily use

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Medical disclaimer: This article is for informational purposes only. It does not constitute medical advice, diagnosis, or treatment. If you have a health condition or take prescription medication, speak with a qualified healthcare provider before adding spearmint tea to your daily routine.

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A familiar herbal drink is not automatically risk-free, but uncertainty is not the same as proven harm. Here is what the studies tell us, where they fall short, and when individual advice helps.

For the full picture on what spearmint tea may do well, see our guide to the evidence behind spearmint tea benefits.

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Spearmint Tea Side Effects: Who Should Avoid It

The hormone studies used tea twice daily for five or 30 days. A 90-day safety trial tested 600 or 900 mg daily of a specific dried extract and found no severe adverse events or significant group difference in reported adverse effects. These preparations are not interchangeable.

Spearmint has a history as a food flavoring. The FEMA assessment concerns specified flavoring uses, not unlimited tea intake or medicinal doses. Small studies cannot reliably measure rare side effects.

Tea bags, loose leaves, capsules, and essential oils differ in composition. Follow the actual product instructions; essential oil is not a substitute for tea.

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Hormonal Effects — the Part Most Articles Get Wrong

What the anti-androgen research shows

A five-day uncontrolled pilot in 21 women with hirsutism found lower free testosterone without a significant reduction in total testosterone. A 30-day randomized trial in 42 women found reductions in both. These studies do not establish which constituent caused the changes.

The studies were small and short. Objective hair-growth scores did not improve significantly between groups in the 30-day trial.

If you want the full breakdown of spearmint’s role in managing hormonal symptoms, we go into detail in our guide on how spearmint tea is used for PCOS.

Concerns for men and people with normal androgen levels

The tea trials in women do not establish effects on testosterone or fertility in men. The 90-day extract trial included men and found no changes in FSH, LH, or TSH. That does not establish that regular tea has no testosterone or fertility effects.

The risk in healthy men is theoretical rather than proven in humans, but it is worth knowing.

Acne or new facial hair deserves assessment: these symptoms do not prove high testosterone. Tea should not replace diagnosis.

These short studies do not establish how long hormone changes persist after stopping.

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Does Spearmint Tea Worsen Acid Reflux?

Spearmint is routinely warned against for acid reflux based largely on evidence that applies to peppermint. The two are frequently conflated.

Peppermint is high in menthol, which relaxes the lower esophageal sphincter (LES) and can allow stomach acid to move upward. Spearmint is low in menthol and high in carvone. One small crossover trial found that spearmint did not significantly affect LES pressure or acid reflux frequency (Bulat et al., 1999), though the evidence is limited.

High amounts did increase symptom scores in that study, likely through direct mucosal irritation rather than reflux. If you have active GERD, monitor your personal response the picture with spearmint is less clear-cut than with peppermint, but individual responses vary.

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Iron Absorption

A human study of polyphenol-containing drinks found reduced non-heme iron absorption from a test meal. It tested peppermint and other herbal teas, but not spearmint, so it cannot quantify the effect of your cup.

If you have iron deficiency or take iron tablets, ask your clinician or pharmacist about timing tea around meals and supplements. Do not change iron treatment based on this indirect evidence.

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Liver and Kidney Considerations

Animal and human findings involve different preparations and doses. The 90-day human extract trial found no relevant blood-chemistry changes. It does not establish safety in people with liver disease.

The evidence cited here does not establish the oxalate content or stone risk of every spearmint product. If you have kidney disease or recurrent stones, check regular herbal-tea use with your clinician.

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Medication Interactions

The studies linked here do not establish a reliable list of clinically confirmed interactions with brewed spearmint tea. Laboratory findings and related plants should not be treated as proof of an interaction.

Tell your pharmacist the product, amount, and medicines you take. Do not stop prescribed treatment. “Hepatotoxic” means capable of damaging the liver, not simply processed by it.

Always tell your pharmacist about any herbal teas you drink regularly, especially if you take prescription medications. This list is not exhaustive and is not a substitute for personalised medical advice.

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Pregnancy, Breastfeeding, and Children

Pregnancy: These trials do not establish pregnancy safety. Ask your maternity clinician before regular use for a health purpose or using concentrated products.

Breastfeeding: Spearmint-specific data are limited. It has not been established that an ordinary cup reduces milk supply; ask about regular use or supplements.

Children: Adult study doses should not be applied to children. Ask a pediatric clinician before using herbal products to treat symptoms.

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Mint-Family Allergies

Allergic reactions are possible. Avoid spearmint if you have a known allergy; do not test it at home. Stop use if a reaction occurs and seek urgent help for breathing difficulty or swelling of the mouth or throat.

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Talk to a Clinician First If…

• You are pregnant or breastfeeding
• You take any prescription medication
• You have a liver condition, kidney disease, or a history of kidney stones
• You are a man with low testosterone or fertility concerns
• You are considering spearmint for hormonal symptoms without a confirmed diagnosis
• You plan to give spearmint tea to a child
• You are scheduled for surgery soon

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The Bottom Line

Short studies provide limited reassurance for their tested preparations and participants. They cannot give everyone a safe daily dose or turn theoretical concerns into documented side effects.

Keep the product label and pay attention to how you feel. Individual advice matters most if you are pregnant, taking medicines, or using tea to manage a health condition.

Frequently Asked Questions