Follistim and Gonal-f belong to the same drug class, which is Gonadotropins; they are used to treat infertility in women, and stimulate the development of multiple eggs. Men can use Follistim.
There is no much difference between these two drugs. They have similar side effects: headache, nausea, stomach, pelvic pain, breast swelling, stuffy nose, skin rash, sore throat numbness, injection site reaction, and others.
However, dizziness is a side effect for Follistim only. Vomiting, swelling of ankles, unusual bleeding from the vagina, pain, redness or swelling of the calf muscles, and others are side effects for Gonal-f only.
It is recommended to start a Gonal drug with 30mg once daily after several days the dosage can be increased to 120mg while it is advisable to start Follistim with 150 to 225 IU for the first four days.