Drug & supplement interaction

Collagen Type Ii (native) + Tadalafil

Tadalafil brand names: Cialis, Tadliq.

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

We found no known interaction between Collagen Type Ii (native) 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Collagen Type Ii (native) 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 Collagen Type Ii (native) 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 Collagen Type Ii (native) 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.

Collagen Type Ii (native) safety at a glance

Collagen Type Ii (... overall Use caution Generally well tolerated in studies, but long-term safety data are limited.
Pregnancy Avoid Not enough safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid Not enough safety information, so it is best avoided while breastfeeding.

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

Still wondering about combining Tadalafil and Collagen Type Ii (native)? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Collagen Type Ii (native) and Tadalafil May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Headache reported in 11.1% of FDA reports for Tadalafil Additional detail

    Collagen Type Ii (native)

    “Orally, headache, dizziness, and insomnia have been reported for patients taking collagen type II in clinical studies, but these events are uncommon.”

    Collagen Type Ii (native) · Natural Medicines adverse-effect record, reported in cluster headache.

    4 sources cited
    1. 44451. Zhang, L. L., Wei, W., Xiao, F., Xu, J. H., Bao, C. D., Ni, L. Q., and Li, X. F. A randomized, double-blind, multicenter, controlled clinical trial of chicken type II collagen in patients with rheumatoid arthritis. Arthritis Rheum 7-15-2008;59(7):905-910 PubMed
    2. 97238. Crowley DC, Lau FC, Sharma P, Evans M, Guthrie N, Bagchi M, et al Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial. Int J Med Sci. 2009 Oct 9;6(6):312-21. PubMed
    3. 97239. Lugo JP, Saiyed ZM, Lane NE. Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study.Nutr J. 2016;15:14. doi: 10.1186/s12937-016-0 PubMed
    4. 101717. Wei W, Zhang LL, Xu JH, et al. A multicenter, double-blind, randomized, controlled phase III clinical trial of chicken type II collagen in rheumatoid arthritis. Arthritis Res Ther. 2009;11(6):R180. PubMed

    Tadalafil

    Listed in the ADVERSE REACTIONS section of the FDA label for Tadalafil, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Stomach pain Additional detail

    Collagen Type Ii (native)

    “Orally, the most common adverse effects of collagen type II reported in clinical studies are gastrointestinal and include constipation, nausea, vomiting, and abdominal pain. These occurred in up to 7% of patients taking collagen type II. Anorexia was also reported, but this was much less common.”

    Collagen Type Ii (native) · Natural Medicines adverse-effect record, reported in anorexia.

    1 source cited
    1. 44451. Zhang, L. L., Wei, W., Xiao, F., Xu, J. H., Bao, C. D., Ni, L. Q., and Li, X. F. A randomized, double-blind, multicenter, controlled clinical trial of chicken type II collagen in patients with rheumatoid arthritis. Arthritis Rheum 7-15-2008;59(7):905-910 PubMed

    Tadalafil

    Listed in the ADVERSE REACTIONS section of the FDA label for Tadalafil. Read the label on DailyMed ›

Reported for Collagen Type Ii (native) but not commonly for Tadalafil: a skin rash, constipation, raised blood pressure and dizziness.

Effects for Tadalafil come from the ADVERSE REACTIONS section of its FDA label; effects for Collagen Type Ii (native) come from the Natural Medicines adverse-effect record, quoted above. 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. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About Collagen Type Ii (native) 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 Collagen Type Ii (native) 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 Collagen Type Ii (native) 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

How much people look this up

Where Collagen Type Ii (native) 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 Collagen Type Ii (native)
Steady interest

#1,292 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 Collagen Type Ii (native) reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Collagen Type Ii (native) and Tadalafil records this page draws on were last updated July 10, 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 Collagen Type Ii (native)

What is Collagen Type Ii (native)?

  • Osteoarthritis and joint pain
  • Joint comfort and mobility
  • Rheumatoid arthritis
  • Exercise-related joint discomfort
  • Joint support in active adults

Native (undenatured) type II collagen is a protein from cartilage, usually chicken, taken in small amounts to support joints, especially in osteoarthritis. Some early research is promising, but the overall evidence is still limited and not conclusive. It appears generally well tolerated, but talk with your pharmacist or doctor before starting it.

Cartilage (often from chicken sternum); collagen protein isolated from cartilage · Capsules, tablets, powders (often labeled UC-II or 'undenatured type II collagen')

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

Collagen Type Ii (native): dosing

There is no official standardized dose, but native type II collagen is unusual because it is used in very small daily amounts — far smaller than typical collagen peptide powders. The exact amount depends on the specific product.The best approach is to follow the directions on the product label and not assume more is better.

From our Collagen Type Ii (native) monograph — the full record covers uses, side effects and every documented interaction.

Read the full Collagen Type Ii (native) 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 & Collagen Type Ii (native)

Browse every other medication we’ve checked against Collagen Type Ii (native) — 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 Collagen Type Ii (native) 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 Collagen Type Ii (native) list.

See the full Collagen Type Ii (native) interactions page
See every supplement checked against Tadalafil, ranked by severity
Evidence & sources

Collagen Type Ii (native) References

The 5 references that drive our Collagen Type Ii (native) 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. Zhang, L. L., Wei, W., Xiao, F., Xu, J. H., Bao, C. D., Ni, L. Q., and Li, X. F. A randomized, double-blind, multicenter, controlled clinical trial of chicken type II collagen in patients with rheumatoid arthritis. Arthritis Rheum 7-15-2008;59(7):905-910 PubMed
  2. Crowley DC, Lau FC, Sharma P, Evans M, Guthrie N, Bagchi M, et al Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial. Int J Med Sci. 2009 Oct 9;6(6):312-21. PubMed
  3. Lugo JP, Saiyed ZM, Lane NE. Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study.Nutr J. 2016;15:14. doi: 10.1186/s12937-016-0 PubMed
  4. Wei W, Zhang LL, Xu JH, et al. A multicenter, double-blind, randomized, controlled phase III clinical trial of chicken type II collagen in rheumatoid arthritis. Arthritis Res Ther. 2009;11(6):R180. PubMed
  5. Thompson DJ, Barron KS, Whitcup SM, Robinson MR. The safety and efficacy of chicken type II collagen on uveitis associated with juvenile rheumatoid arthritis. Ocul Immunol Inflamm. 2002;10(2):83-91. 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 Collagen Type Ii (native) and Tadalafil Together: Common Questions

Is it safe to take Collagen Type Ii (native) with Tadalafil?
We do not list a known interaction between Collagen Type Ii (native) 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.
Do Collagen Type Ii (native) and Tadalafil have any of the same side effects?
Yes — our sources link each of them separately to 2 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Does Tadalafil interact with any supplements?
Yes. Tadalafil has documented interactions with 144 supplements in our database — Collagen Type Ii (native) 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

Collagen Type Ii (native) 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 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Tadalafil and Collagen Type Ii (native)?

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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.