Follistatin

Intramuscular injection can cause localised discomfort, mild bruising, or soreness at the injection site. This typically resolves within 24-48 hours. Rotating sites and allowing the solution to reach room temperature before injection may reduce discomfort.

Some users report mild swelling or hardening at the injection site. This is usually self-resolving within a few days. Ensure proper injection technique and site rotation to minimise this effect.

Increased muscle soreness beyond normal training-induced soreness may occur, particularly in the early weeks of use. This is distinct from injection site soreness and may reflect rapid muscle growth or inflammation.

Some users report mild joint discomfort, particularly in the knees or shoulders. This may be related to rapid increases in muscle mass and strength outpacing connective tissue adaptation. Ensure adequate recovery and consider joint support supplementation.

Mild headaches have been reported in some users. These are typically self-resolving and may be related to systemic effects of myostatin inhibition or dehydration.

Increased sebum production or acne may occur, likely related to hormonal changes or increased metabolic activity. Maintain good skin hygiene and consider dermatological consultation if severe.

Mild gastrointestinal symptoms have been reported rarely. These are typically self-resolving. Ensure adequate hydration and food intake.

Repeated injections into the same site can cause localised fat loss or atrophy of subcutaneous tissue. This is preventable through strict site rotation. Always rotate injection sites and maintain at least 1 inch between previous injection points.

Repeated intramuscular injections into the same site can lead to fibrosis or scar tissue formation, which may impair muscle function. Prevent this through consistent site rotation and proper injection technique.

Poor injection technique or non-sterile conditions can lead to bacterial infection or abscess formation. Signs include increasing pain, redness, warmth, swelling, or drainage at the injection site. Seek immediate medical attention if infection is suspected. Always use sterile technique and dispose of needles safely.

Although rare, allergic reactions to follistatin or excipients are possible. Signs include rash, itching, swelling of face or throat, difficulty breathing, or anaphylaxis. Seek immediate medical attention if any signs of allergic reaction occur. Discontinue use immediately.

Systemic inflammatory responses or low-grade fever have been reported rarely. This may reflect immune activation or systemic effects of myostatin inhibition. Monitor temperature and seek medical evaluation if fever persists or is accompanied by other symptoms.