Mullein has a quiet safety record across centuries of use, and that is genuinely reassuring. It also reflects how little it has been studied: 148 papers, 3 trials.
There is 1 exclusion every reference source agrees on, and 1 irritation almost everyone causes themselves.
Quick Answer: What Are the Side Effects of Mullein?
Reported side effects are mild and uncommon, mostly throat irritation from unstrained leaf hairs and occasional stomach upset or skin reaction. The one exclusion every reference source states is pregnancy and breastfeeding. Because only 3 clinical trials of mullein exist and none ran long term, the reassuring safety picture rests on traditional use rather than on monitoring.
Key Takeaways
- The 1 universal exclusion is pregnancy and breastfeeding, in every format.
- Throat irritation is usually self-inflicted, from 1 skipped straining step.
- 0 long-term safety studies of mullein exist, in any format.
- The FDA reviews 0 supplements for safety or for proven effectiveness.
- Contact dermatitis is 1 reaction reported occasionally with the fresh plant.
Related Products
The Everyday Picture
Across centuries of use and 3 trials, mullein has not produced dramatic reports.
- Most common: Throat scratchiness, from hairs left in the tea.
- Occasional: Mild stomach upset.
- Occasional: Skin irritation from handling the fresh plant.
- Rare: Allergic reaction, as with any botanical.
A 2022 review records centuries of use for lung, skin and throat complaints with no safety signal attached to it.[1]Health-promoting and disease-mitigating potential of Verbascum thapsus L. (common mullein): A review — Phytotherapy Research (2022) View source That is reassuring, and it is not the same thing as monitoring.
None of that is trivial if it happens to you, and none of it is the profile of a risky herb. What the plant is in the first place is in the mullein explainer.
The Hairs Are the Main Problem
The single most common complaint about mullein is avoidable in one step.
- What they are: Dense branching hairs covering the leaf surface.
- What they do: Pass through coarse infusers and scratch the throat.
- Who notices: Anyone brewing loose leaf without a fine filter.
- The fix: A paper coffee filter or muslin, every time.
Straining properly is covered step by step in the tea and how to strain it. A capsule sidesteps the issue entirely, because the leaf never touches your throat.
Who Should Skip It
The exclusion list is short and the first entry is not negotiable.
| Group | Position |
|---|---|
| Pregnant or breastfeeding | Avoid, in every form including tea |
| Diagnosed COPD, asthma or emphysema | Do not self-start, ask the clinician managing it |
| Known allergy to Scrophulariaceae plants | Avoid |
| Children | Not for self-treatment, ask a paediatrician |
| Anyone with a cough over 3 weeks | Get examined before treating it |
WebMD states the pregnancy and breastfeeding exclusion plainly and also notes that mullein's benefits are not well defined, which is a fair summary of both halves of this page. The 1 trial that tested mullein alone in people used it topically, in 93 women after childbirth.[2]The effect of the Verbascum Thapsus on episiotomy wound healing in nulliparous women: a randomized controlled trial — BMC Complementary Medicine and Therapies (2021) View source
What Not to Mix It With
This question comes up constantly and the accurate answer is unsatisfying.
- Documented interactions: 0 clinically established ones.
- Why that is not reassurance: 0 interaction studies have been done.
- Sensible caution: Space it from prescription medicines by 2 hours.
- Always ask about: Anything for the heart, blood pressure or breathing.
The constituents that would drive an interaction have been catalogued, but only in glassware.[3]The Antioxidant, Anticarcinogenic and Antimicrobial Properties of Verbascum thapsus L. — Medicinal Chemistry (2021) View source None has been followed into a person taking a prescription.
An absence of reported interactions in a herb nobody has run interaction studies on is missing data, not a clean bill of health. Amounts and formats are in the safety cautions.
Is It Safe Every Day
Probably, on tradition. Certainly not on data, because the data does not exist.
- Longest human trial: Weeks, and it was a topical dressing.
- Long-term oral studies: 0.
- Traditional pattern: Used for a complaint, not taken indefinitely.
- Reasonable default: Use it while you need it, then stop.
For everyone outside the excluded groups, our 60-capsule bottle has an undramatic record.
See a Clinician Rather Than Continuing If
- Pregnancy or breastfeeding, which is the one exclusion every reference source states
- A diagnosis of COPD, asthma or emphysema, where a herb does not replace an inhaler
- Shortness of breath that is new, worsening or waking you at night
- Coughing up blood, or a cough that has lasted more than 3 weeks
- Any plan to smoke the leaf, whatever the reason
Frequently Asked Questions
What are the side effects of using mullein? +
Mild and uncommon: throat scratchiness from unstrained hairs, occasional stomach upset, and occasional skin irritation. Across 3 trials and centuries of use, serious reports are rare.
When should you not drink mullein tea? +
In pregnancy and while breastfeeding, the 1 exclusion every source states. Also if a cough has run more than 3 weeks.
What not to mix with mullein? +
There are 0 clinically established interactions, because 0 interaction studies exist. Space it 2 hours from prescription medicines and ask about heart, blood pressure and breathing drugs.
Is mullein safe to take every day? +
Tradition says yes and data says nothing, because 0 long-term oral studies exist. Using it while you need it is the safer default.
Can mullein irritate your throat? +
Yes, and it is the most common complaint. The leaf hairs cause it, and 1 pass through a paper filter prevents it.
Is mullein safe in pregnancy? +
No. It is the 1 exclusion that every reference source agrees on, and it applies to tea as well as capsules.
Can children take mullein? +
Not for self-treatment. The 2 paediatric trials that exist tested an ear drop containing 4 herbs, not anything swallowed.
Does mullein interact with blood pressure medication? +
No interaction has been documented, and 0 studies have looked. Ask the prescriber before combining them.
Is mullein FDA approved? +
No. The FDA does not review dietary supplements for safety or effectiveness, which covers all 60 capsules.
Can you be allergic to mullein? +
Yes, as with any botanical. Contact dermatitis from the fresh plant is the 1 reaction reported most often.
Related Reading
- The Lung Question, Answered Honestly
- Mullein and the Smoking Question
- Which Lung Herb Is Actually Best?
Related Products
