Short answer

We found no direct interaction between Cordyceps and Vitamin D3 with A, E and K2 in the sources below, but they share a caution.

Both have a note about blood thinners such as warfarin (see each one below).

Cordyceps

What it is: A fungus that grows on moth caterpillars, used in traditional Chinese medicine for energy and immunity.

What the research says: Some studies looked at kidney function in transplant and diabetes patients, but reviews question the quality of the evidence. Most research is in the lab.

Cautions

• No major side effects have been reported.

Medicines to check

• Insulin and other blood-sugar-lowering medicines: cordyceps may lower blood sugar too
• Blood thinners such as warfarin: it may raise bleeding risk

In Holitro: Cordyceps (500 mg per capsule)

Source: Memorial Sloan Kettering Cancer Center, About Herbs: Cordyceps (updated February 2022)

Vitamin D3 with A, E and K2

What it is: A combination of vitamin D3 with vitamins A, E and K2. Vitamin D helps the body absorb calcium and supports muscles, nerves and the immune system.

What the research says: Getting enough vitamin D and calcium helps protect against osteoporosis.

Cautions

• Adults shouldn't exceed 4,000 IU (100 mcg) of vitamin D a day from all sources unless a clinician advises more. Too much can cause nausea, weakness, confusion and kidney stones.
• Too much preformed vitamin A can cause headaches and blurred vision, and birth defects in pregnancy.
• High-dose vitamin E supplements may raise bleeding risk.

Medicines to check

• Warfarin: vitamin K and vitamin E both matter, and vitamin K intake should stay steady
• Statins, steroids, orlistat and thiazide diuretics (vitamin D notes)
• Vitamin A-based medicines such as acitretin

In Holitro: D Complex (5,000 IU per capsule)

Sources: NIH Office of Dietary Supplements: Vitamin D: Fact Sheet for Consumers (updated November 2022); NIH Office of Dietary Supplements: Vitamin A: Fact Sheet for Consumers (updated March 2025); NIH Office of Dietary Supplements: Vitamin E: Fact Sheet for Consumers (updated March 2021); NIH Office of Dietary Supplements: Vitamin K: Fact Sheet for Consumers (updated March 2021)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.