Follistatin-344 side effects and risks

Reported side effects

• Retinal fluid leakage and blurred vision: 11 selected eye cases after reported 1 mg injections; user wide incidence unknown., serious. Stop injections and seek urgent eye assessment for new blur, distortion or a dark spot. (source)
• Injection pain, swelling and fever-like symptoms: Reported in one self use log; no reliable rate., moderate. Stop further exposure and seek assessment for marked swelling, persistent fever or worsening pain. (source)
• Immune reactions or contaminants: Human rates are unknown; market testing found wrong proteins and manufacturing tags., serious. Breathing trouble or facial swelling needs emergency care. (source)
• Reproductive-hormone effects: Activin binding creates a mechanistic concern; human protein injection risk is unknown., moderate. Review fertility plans and menstrual or sexual changes with a clinician. (source)
• Raised LDL after plasmid gene delivery: Unreviewed 43 person manuscript reports mean LDL +11.6 mg/dL at three months., moderate. This gene-therapy finding cannot be assigned to protein-vial use. (source)

Stop and get help if

• New blurred or distorted vision, or a central dark spot: Stop injections and get urgent eye care today.
• Breathing trouble, fainting, or swelling of the face or tongue: Call emergency services now; stop further exposure.
• Fever with a hot, expanding injection-site swelling or severe pain: Stop injections and get urgent medical assessment.

Who should avoid it

• pregnant: No pregnancy safety data for protein injections; gene-therapy trials exclude pregnancy.
• breastfeeding: No infant-exposure or breastfeeding safety data; excluded in the current AAV trial.
• tryingToConceive: Activin affects reproductive signaling; safe fertility exposure and washout are unknown.
• under18: Adult self-use protocols exclude minors; three pediatric gene-transfer cases do not establish protein-injection safety.
• activeCancer: Current gene-therapy trial excludes active or recent cancer. Protein effects on cancer growth are unresolved.
• cancerHistory: Recent cancer is excluded from current gene-therapy research; long-term recurrence risk is unknown.
• other: Reported high-dose use is linked to retinal fluid leakage; avoid further exposure with active or prior disease.
• liverDisease: Human protein dosing in liver disease is unstudied; gene-transfer studies monitor liver tests.
• kidneyDisease: Dose changes in kidney disease are unknown; gene-transfer studies monitor kidney function.
• immunosuppressed: Product sterility and immune risks are unresolved; AAV studies require specialized immune screening.
• surgeryPlanned: No perioperative safety or validated washout for protein injections was found.
• testedAthlete: Follistatin is prohibited at all times under WADA S4.3; gene transfer may also fall under M3.

Interactions

• Corticosteroids: Both exposures are linked to retinal fluid leakage. Additive risk is a precaution; no combination trial exists.
• Other myostatin or activin blockers: Overlapping growth-signal blockade has unknown combined risks. No human trial supports stacking these products.
• Growth hormone and IGF products: Discussed together for muscle gain; no human trial establishes safety or added benefit with injected follistatin.

Product quality risks

• Only 9/17 tested products contained follistatin; all nine had His-tags and many protein oligomers.
• Other tested products contained growth-related peptides such as MGF or GHRP-2.
• The label does not establish identity, amount, biological activity, sterility or endotoxin safety.