Drug & supplement interaction

Fireweed + Tadalafil

Tadalafil brand names: Cialis, Tadliq.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Fireweed and Tadalafil in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Fireweed and Tadalafil

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Tadalafil and Fireweed in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Fireweed at all — not against Tadalafil, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Fireweed safety at a glance

Fireweed overall Use caution Generally considered low-risk as a tea, but human safety data are limited.
Pregnancy Avoid Not enough safety information, so it is best to avoid it.
Breastfeeding Avoid Safety has not been established, so avoid use while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Tadalafil and Fireweed? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Tadalafil’s Own FDA Label Lists

This is not an interaction — none of it involves Fireweed. These are the most notable effects listed in the ADVERSE REACTIONS section of Tadalafil’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both.

  • Flushing
  • A stuffy or runny nose
  • Back pain
  • Muscle pain
  • Stomach upset
  • Headache mentioned in 11.1% of FDA reports for Tadalafil
  • Stomach pain

From the ADVERSE REACTIONS section of the FDA label for Tadalafil. Read the label on DailyMed › Where a percentage is shown, it is the share of 98,103 voluntary FDA FAERS reports for Tadalafil that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Fireweed’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Fireweed side to compare — that is a limit of the record, not a statement that Fireweed has no side effects.

From our Q&A

Questions About Fireweed or Tadalafil

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Fireweed or Tadalafil, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Tadalafil

This page covers Fireweed only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tadalafil page lists 144 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Grapefruit (major), Hawthorn (major) and St. John's Wort (major).

By severity: 5 major · 98 moderate · 41 minor.

From our pharmacist’s overview on the Tadalafil page

“Grapefruit juice is the first thing to know about if you take tadalafil (Cialis, Tadliq). It blocks CYP3A4, the enzyme that clears the drug, so blood levels climb and side effects like a steep drop in blood pressure become more likely.”

Reviewed by 2 · Jul 18, 2026

Open the Tadalafil interaction page

One more smart check

Taking Fireweed as Part of a Dietary Supplement Product? Check It for Interactions

We hold 5 real supplement products containing Fireweed, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Fireweed. Even though Fireweed itself has no known interaction with Tadalafil, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Fireweed and Tadalafil Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Fireweed
Steady interest

#769 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Tadalafil
Top 1%

#16 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Fireweed reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Fireweed and Tadalafil records this page draws on were last updated June 22, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Fireweed

What is Fireweed?

  • Prostate and urinary symptoms
  • Digestive upset and diarrhea
  • Skin irritation (topical)
  • Sore throat and mouth inflammation
  • General anti-inflammatory support

Fireweed is a wild flowering plant used traditionally as a tea and folk remedy, most often for prostate, urinary, digestive, and skin complaints. Human evidence is very limited, so its benefits are not well proven. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Epilobium angustifolium · Onagraceae · Aerial parts (leaves, flowers, and stems); a related species, Epilobium parviflorum, is often used for prostate concerns · Tea, dried herb, tincture, capsules, topical preparations

An interaction check asks whether these two react with each other — it does not ask whether Fireweed is a good idea for someone in your situation. Here is what our Fireweed record says about it on its own.

Fireweed: dosing

There is no well-established standardized dose for fireweed. Traditional use often involves a tea made from the dried leaves, while supplements come in capsules or tinctures with varying strengths.Because products differ so much, the safest approach is to follow the directions on the product label and not exceed the recommended amount. A pharmacist can help you review a specific product and decide whether it is appropriate for you.If you do not notice benefit, or you have ongoing symptoms, see a healthcare provider instead of increasing the dose on your own.

From our Fireweed monograph — the full record covers uses, side effects and every documented interaction.

Read the full Fireweed monograph & all interactions
Medication

About Tadalafil

What Is Tadalafil Used For?

Brand names: Cialis, Tadliq

Tadalafil tablets (including Cialis and generic tadalafil) are used to treat erectile dysfunction (ED), the symptoms of benign prostatic hyperplasia (BPH — an enlarged prostate), or both conditions together. When used with the drug finasteride to start BPH treatment, this combination is recommended for up to 26 weeks.

Adcirca, Alyq (tablets), and Tadliq (oral suspension) are indicated specifically for pulmonary arterial hypertension (PAH — high blood pressure in the lungs), to improve the ability to exercise.

Most-Reported Side Effects for Tadalafil

From FAERS, the FDA’s public side-effect reporting system (99,210 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 11,917 reports
Headache 10,982 reports
Diarrhea 8,020 reports
Nausea 6,697 reports
Fatigue 6,080 reports
See full Tadalafil drug information
Keep checking

Other Drugs & Fireweed

Browse every other medication we’ve checked against Fireweed — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

We also checked Fireweed against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Fireweed list.

See the full Fireweed interactions page
See every supplement checked against Tadalafil, ranked by severity
Evidence & sources

Fireweed References

The 1 references that drive our Fireweed monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Esposito C, Santarcangelo C, Masselli R, et al. Epilobium angustifolium L. extract with high content in oenothein B on benign prostatic hyperplasia: A monocentric, randomized, double-blind, placebo-controlled clinical trial. Biomed Pharmacother. 2021 Jun; PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Fireweed and Tadalafil Together: Common Questions

Is it safe to take Fireweed with Tadalafil?
We do not list a known interaction between Fireweed and Tadalafil. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Does Tadalafil interact with any supplements?
Yes. Tadalafil has documented interactions with 144 supplements in our database — Fireweed is not one of them. The Tadalafil interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Fireweed monograph Uses, safety profile, and every drug interaction in one place Tadalafil drug information The full plain-English guide to this medication Tadalafil supplement interactions Every supplement checked against Tadalafil, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Tadalafil and Fireweed?

Our pharmacists answer your medication & supplement questions — free.

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.