Spearmint Tea Side Effects + Who Should Avoid It

Key Takeaways

• Spearmint tea side effects are uncommon at typical amounts, but certain groups have meaningful considerations
• Its anti-androgenic properties are a benefit for some women, and a potential concern for men
• Spearmint behaves differently from peppermint when it comes to acid reflux
• Some prescription medications may interact with spearmint, always check with your pharmacist
• Long-term safety data beyond a few months simply does not exist

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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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Spearmint tea side effects are uncommon for most people, but a few groups should be cautious. This page covers every documented risk, the populations who genuinely need to think twice, and the medication categories that may interact with spearmint, without the panic, and without burying the answer below eight paragraphs of benefits.

For the full picture on what spearmint tea may do well, see our guide to the well-documented benefits of spearmint tea.

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Spearmint Tea Side Effects: Who Should Avoid It

Most clinical trials used 2 cups per day for up to 30 days. One extended safety trial tested a 900 mg dried aqueous extract daily for 90 days and found no serious adverse events (Lasrado et al., 2017). That is the current ceiling of human safety data.

At 1–2 cups per day, spearmint tea is well-tolerated in healthy adults across all completed human trials. Mild digestive upset is occasionally reported but not consistently documented in controlled settings. Spearmint is also widely used as a food flavouring and considered safe at typical dietary amounts by major food safety authorities.

The picture shifts with concentrated supplements. Serving sizes vary by brand (tea bags vs loose leaf), so treat brewed tea as a lower-dose option than standardized extracts. If you’re using extracts rather than brewed tea, the risk calculus changes, and the safety data is thinner.

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Hormonal Effects — the Part Most Articles Get Wrong

What the anti-androgen research shows

Spearmint contains compounds, primarily rosmarinic acid and flavonoids, that interact with androgen activity. Two clinical trials in women with PCOS and hirsutism found that 2 cups per day reduced free testosterone and increased LH, FSH, and estradiol over 5–30 days (Akdoğan et al., 2007; Grant et al., 2010).

That sounds clear-cut. It is not, quite. Both trials were small (n=21 and n=42), short in duration, and conducted in women with confirmed elevated androgens. Objective hirsutism scores actual unwanted hair did not significantly improve in the 30-day window.

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

No human clinical trial has tested spearmint’s effects in healthy men. Animal studies found that high-dose chronic administration may reduce testosterone and alter sperm parameters (Nozhat et al., 2014). The 90-day human safety trial in healthy adults found no changes in FSH, LH, or TSH (Lasrado et al., 2017) the most likely reason being that anti-androgenic effects are more pronounced when baseline androgens are already elevated.

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

A less-discussed concern: some people drink spearmint tea daily for acne or facial hair without confirming through bloodwork that elevated androgens are the cause. If your levels are already normal, suppressing them further is not a neutral act. No human study has specifically tested this consider it a flag worth raising with your doctor.

One thing nobody states clearly: whether spearmint’s hormonal effects reverse after stopping consumption has not been studied.

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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

Spearmint tea is rich in polyphenols, which can inhibit non-heme (plant-based) iron absorption. Research shows that polyphenol-containing beverages may meaningfully reduce non-heme iron uptake (Hurrell et al., 1999). Heme iron from meat is largely unaffected.

The practical fix is simple: drink spearmint tea between meals rather than alongside iron-rich food or iron supplements, and the effect is substantially reduced. This matters most for people managing iron-deficiency anemia, vegans, vegetarians, and menstruating women.

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Liver and Kidney Considerations

Animal studies found dose-dependent liver cell changes at high chronic doses of spearmint (Akdoğan et al., 2004). The 90-day human safety trial contradicts this at study-level doses, showing no liver enzyme changes. People with pre-existing liver disease should not rely on that reassurance without speaking to a clinician.

For kidneys, herbal teas contain modest oxalate levels compared to black tea (Savage et al., 2003). Spearmint is not a high-oxalate food. Still, people with kidney disease or a history of calcium oxalate kidney stones should discuss regular herbal tea consumption with their doctor.

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Medication Interactions

Some medication categories may interact with spearmint based on its known pharmacological activity. Rather than listing specific drug names which depends on your full medication profile, here are the categories to be aware of:

• Hepatotoxic medications (drugs that are processed by the liver) possible additive liver stress
• Sedatives and CNS depressants – possible additive drowsiness
• Diabetes medications – possible interaction; discuss with your prescriber
• Hormonal medications (including contraceptives and HRT) – possible compounded hormonal effects
• Anticoagulants and anti-hypertensives – weak theoretical interactions extrapolated from related plants

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: Large amounts are classified as possibly unsafe based on animal data showing uterine tissue effects at high doses (Güney et al., 2006). Human safety data is limited. If you’re pregnant, keep intake conservative and check with your OB-GYN or midwife especially if you plan to drink it daily. Concentrated extracts and supplements should be avoided.

Breastfeeding: Insufficient reliable data exists. Sticking to occasional food-level amounts is the conservative approach.

Children: No clinical safety data exists. The anti-androgenic properties add an additional reason for caution during development. Consult a healthcare provider before giving herbal teas to children.

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Mint-Family Allergies

Spearmint belongs to the Lamiaceae family, alongside basil, oregano, thyme, rosemary, and sage. Allergic reactions are possible. If you have known mint-family allergies or pollen allergies, introduce spearmint cautiously and stop if you notice symptoms. Seek urgent care for severe reactions.

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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

Spearmint tea is well-tolerated by most healthy adults at typical amounts. The side effects that do exist are real but specific they apply to particular groups, particular health conditions, and particular combinations with medication, not to everyone who brews a cup.

The two areas worth taking seriously regardless of your health status: if you take prescription medication, mention spearmint to your pharmacist, and if you are pregnant, check with your OB-GYN before making it a daily habit. For everyone else, the evidence supports enjoying it without worry just without the assumption that more is always better.

Frequently Asked Questions