When to Stop

• Bleeding events / antiplatelet effect. Cordycepin and adenosine analogs exhibit weak antiplatelet activity in vitro. Real-world bleeding risk at supplement doses is theoretical, not well-documented in case reports. The 2022 *Proc Baylor Univ Med Cent* review on dietary supplements and bleeding (PMID 36304597) loosely associates *C. sinensis* with surgical bleeding independent of anticoagulants. Stop 10-14 days before surgery, fights with high contact risk, or anything involving anticoagulant interaction.
• Allergic / hypersensitivity reaction. Rare but documented — usually in mushroom-allergic individuals. Discontinue immediately if rash, swelling, or breathing difficulty.
• Heavy-metal contamination (wild C. sinensis specifically). Wild Tibetan caterpillar fungus is harvested in areas with high arsenic/cadmium soil burden, and supply-chain analyses have documented lead and arsenic contamination above WHO limits in multiple wild-source samples. Farmed *C. militaris* avoids this entirely — one more reason to skip wild Cs-4.
• Adulteration with prescription drugs. Less common than in pre-workout products, but cordyceps blends marketed for "energy" have been spot-checked positive for sildenafil analogs, ephedrine, and caffeine. Stick to reputable supply chains.
• Weeks 1-2: GI tolerance and dose calibration. If GI upset persists, drop dose by 50% or switch product (mycelium-on-grain → fruiting body extract).
• Pre-event (10-14 days before competition / surgery): Stop. Even though clinical bleeding case reports are absent, the antiplatelet mechanism is real and a fight-camp injury could be aggravated.
• First-time use: Avoid coadministering with a new anticoagulant, new antidepressant, or new thyroid medication in the same week — see Drug Interactions for the relevant pairs.