Drug & supplement interaction

Cardarine + Hydroxyurea

Hydroxyurea brand names: Droxia, Hydrea, Siklos, Xromi.

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 Cardarine and Hydroxyurea 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

Cardarine and Hydroxyurea

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 Hydroxyurea and Cardarine 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 Cardarine at all — not against Hydroxyurea, 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.

Cardarine safety at a glance

Cardarine overall Avoid Animal studies linked it to cancer and it is not approved or proven safe for human use.
Pregnancy Possibly Unsafe When used orally or parenterally. Some metabolic modulators have been found to cause cancer in animals. Their safety in humans has not been tested. Avoid using. Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally or parenterally. Some metabolic modulators have been found to cause cancer in animals. Their safety in humans has not been tested. Avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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

What Hydroxyurea’s Own FDA Label Lists

This is not an interaction — none of it involves Cardarine. These are the most notable effects listed in the ADVERSE REACTIONS section of Hydroxyurea’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. 6 of them are worth acting on rather than waiting out — marked below.

  • Low magnesium Worth acting on
  • Anemia Worth acting on mentioned in 12.0% of FDA reports for Hydroxyurea
  • A low platelet count Worth acting on
  • Shortness of breath Worth acting on
  • A low white blood cell count Worth acting on
  • A higher chance of infection Worth acting on
  • Changes to your period
  • Dry skin
  • Weight gain
  • Pain in an arm or leg

Showing the 10 most notable of 25 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Hydroxyurea. Read the label on DailyMed › Where a percentage is shown, it is the share of 21,027 voluntary FDA FAERS reports for Hydroxyurea that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Cardarine’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Cardarine side to compare — that is a limit of the record, not a statement that Cardarine has no side effects.

Special populations

Cardarine in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally or parenterally. Some metabolic modulators have been found to cause cancer in animals. Their safety in humans has not been tested. Avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Cardarine or Hydroxyurea

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Cardarine or Hydroxyurea, 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 Hydroxyurea

This page covers Cardarine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydroxyurea page lists 18 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 10 minor.

From our pharmacist’s overview on the Hydroxyurea page

“People take hydroxyurea (Droxia, Hydrea, Siklos, Xromi) for serious reasons, most often sickle cell disease or certain blood cancers, and it only works if a steady dose reaches the bloodstream. That is exactly what nearly all 18 supplements listed here can undermine, so this page earns real vigilance rather than a skim.”

Reviewed by 2 · Jul 18, 2026

Open the Hydroxyurea interaction page

One more smart check

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

We hold 18 real supplement products containing Cardarine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cardarine. Even though Cardarine itself has no known interaction with Hydroxyurea, 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 Cardarine and Hydroxyurea 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 Cardarine
Steady interest

#1,179 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Hydroxyurea
Top 5%

#39 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 Cardarine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Cardarine and Hydroxyurea 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 Cardarine

What is Cardarine?

  • Endurance and athletic performance
  • Fat loss and body recomposition
  • Bodybuilding cycles
  • Increasing exercise capacity

Cardarine (GW501516) is a synthetic experimental drug, not a vitamin, herb, or true dietary supplement, even though it is often sold as one. Animal studies linked it to a higher risk of cancer, drug development was halted, and it is banned in sports — so it should not be used. There is no proven safe dose for humans.

Not applicable (synthetic chemical compound) · Capsules, tablets, oral liquids, powders (sold as a 'research chemical')

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

Cardarine: dosing

There is no established safe or approved dose of Cardarine for humans. It is not approved by the FDA for any condition, and no medical or pharmacy authority endorses a dosing plan.Doses listed on websites and forums are not based on reliable safety research and should not be trusted.

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

Read the full Cardarine monograph & all interactions
Medication

About Hydroxyurea

What Is Hydroxyurea Used For?

Brand names: Droxia, Hydrea, Siklos, Xromi

Hydroxyurea is used for several serious conditions. Droxia, Siklos, and Xromi are each indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is approved for adults and children 2 years and older; Xromi is approved for children 6 months and older; Droxia is approved for adults.

Hydrea capsules and Hydroxyurea capsules are indicated for resistant chronic myeloid leukemia and for locally advanced squamous cell carcinomas of the head and neck (excluding the lip) when used together with chemoradiation.

Most-Reported Side Effects for Hydroxyurea

From FAERS, the FDA’s public side-effect reporting system (21,027 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 1,548 reports
Sickle cell anaemia with crisis 1,486 reports
Diarrhea 1,408 reports
Nausea 1,306 reports
Headache 1,068 reports
See full Hydroxyurea drug information
Keep checking

Other Drugs & Cardarine

Browse every other medication we’ve checked against Cardarine — 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 Cardarine 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 Cardarine list.

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

Cardarine References

The 1 references that drive our Cardarine 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. What Should Tested Athletes Know About GW1516? Education, Spirit of Sport. U.S. Anti-Doping Agency (USADA). September 24, 2019. Available at: https://www.usada.org/spirit-of-sport/education/what-should-athletes-know-gw1516/

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 Cardarine and Hydroxyurea Together: Common Questions

Is it safe to take Cardarine with Hydroxyurea?
We do not list a known interaction between Cardarine and Hydroxyurea. 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 Hydroxyurea interact with any supplements?
Yes. Hydroxyurea has documented interactions with 18 supplements in our database — Cardarine is not one of them. The Hydroxyurea 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

Cardarine monograph Uses, safety profile, and every drug interaction in one place Hydroxyurea drug information The full plain-English guide to this medication Hydroxyurea supplement interactions Every supplement checked against Hydroxyurea, 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 Hydroxyurea and Cardarine?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.