Would like to switch to st.johns wort from 20mg of prozac (fluoxetine) because of side effects been on prozac (fluoxetine) for 8 mos. how soon could i do this?

Thirty-Five Days: Every medication has a half-life. This is the time it takes the body to eliminate one half of the med. I consider a medication to be eliminated after 5 half-lives. When the body begins to breakdown prozac, (fluoxetine) one of the byproducts is an active metabolite that has a half-life of 7 days. It takes about 35 days for total elimination. One should not take st. John's wort until Prozac (fluoxetine) is eliminated.