Drug & supplement interaction

Astaxanthin + Tadalafil

Tadalafil brand names: Cialis, Tadliq.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Astaxanthin has a moderate interaction with Tadalafil. Theoretically, astaxanthin may decrease levels of drugs metabolized by CYP3A4.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Astaxanthin and Tadalafil

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Tadalafil

Tadalafil falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Astaxanthin interacts with.

Theoretically, astaxanthin may decrease levels of drugs metabolized by CYP3A4.
In vitro research shows that astaxanthin induces CYP3A4 enzyme activity in human hepatocytes. This effect has not been reported in humans.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist if you take tadalafil (Cialis) and want to add astaxanthin. Your body clears tadalafil using a liver enzyme called CYP3A4. In lab studies using human liver cells, astaxanthin seemed to speed up that enzyme a bit. If that happened in a real person, tadalafil could be broken down faster and not work as well, so you might notice a weaker response for ED or your BPH symptoms.

The key thing is this is only test-tube data and has never actually been shown in people, so I wouldn't lose sleep over it. Tadalafil isn't a prodrug, so the direction makes sense (faster clearance, less effect). Before starting astaxanthin, just run it by your pharmacist or doctor so they can keep an eye on how well your tadalafil is working.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kistler, A., Liechti, H., Pichard, L., Wolz, E., Oesterhelt, G., Hayes, A., and Maurel, P. Metabolism and CYP-inducer properties of astaxanthin in man and primary human hepatocytes. Arch.Toxicol. 2002;75(11-12):665-675. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Astaxanthin Also Interacts With Other Medications

Astaxanthin has 670 moderate known drug interactions in our database — the Tadalafil one above is one of them. If you take anything else, check it against the full list below.

Moderate 670 No known interaction 2,160 (incl. Tadalafil)
Taking anything else?

Check Another of Your Medications Against Astaxanthin

Covers the 2,830 medications we’ve checked against Astaxanthin. Pick one to open its full report.

From our Q&A

Questions About Astaxanthin 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 Astaxanthin 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 Astaxanthin 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 Astaxanthin as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2,223 real supplement products containing Astaxanthin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Astaxanthin. Your product may carry other ingredients that interact with Tadalafil too, on top of Astaxanthin — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Astaxanthin 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 Astaxanthin
Top 10%

#95 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.

Supplement

About Astaxanthin

What is Astaxanthin?

Astaxanthin
  • Antioxidant support
  • Skin health and aging
  • Eye health
  • Exercise recovery
  • Heart and inflammation support

Astaxanthin is a reddish carotenoid pigment with strong antioxidant activity in the lab, and it is widely promoted for skin, eye, heart, and exercise benefits. Early human studies are promising for a few uses, but the overall evidence is still limited and not strong enough to make firm claims. It appears generally well tolerated at typical supplement doses, but talk with your pharmacist or doctor before starting it.

Read the full Astaxanthin 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.

See full Tadalafil drug information
Keep checking

Other Drugs & Astaxanthin

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

0Major
670Moderate
0Minor
2,159No known interaction
670 Moderate 2,159 No interaction
Moderate

670 interactions

Showing 60 of 670 moderate interactions — see all 670 on the Astaxanthin page.

No interaction 2,159 drugs checked — show the list

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

Showing the 60 most looked-up of 2,159 medications checked with no known interaction — see the full Astaxanthin list.

See the full Astaxanthin interactions page
See every supplement checked against Tadalafil, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Astaxanthin monograph › Uses, safety, and every drug interaction in one place Tadalafil supplement interactions › Every supplement checked against Tadalafil, ranked by severity Tadalafil drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Astaxanthin and Tadalafil Together: Common Questions

Can you take Astaxanthin with Tadalafil?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Astaxanthin and Tadalafil interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Tadalafil and Astaxanthin?

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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.