different levels of diligence by users. Methods with little or nothing to do or remember, or that require a clinic visit less than once per year are said to be non-user dependent, forgettable or top-tier methods. Intrauterine methods, implants, and sterilization fall into this category. For methods that are not user dependent, the actual and perfect-use failure rates are very similar. Many hormonal methods of birth control, and LAM require a moderate level of thoughtfulness. For many hormonal methods, clinic visits must be made every three months to a year to renew the prescription. The pill must be taken every day, the patch must be reapplied weekly, or the ring must be replaced monthly. Injections are required every 12 weeks. The rules for LAM must be followed every day. Both LAM and hormonal methods provide a reduced level of protection against pregnancy if they are occasionally used incorrectly (rarely going longer than 4–6 hours between breastfeeds, a late pill or injection, or forgetting to replace a patch or ring on time). The actual failure rates for LAM and hormonal methods are somewhat higher than the perfect-use failure rates. Higher levels of user commitment are required for other methods. Barrier methods, coitus interruptus, and spermicides must be used at every act of intercourse. Fertility awareness-based methods may require daily tracking of the menstrual cycle. The actual failure rates for these methods may be much higher than the perfect-use failure rates. Side effects Different forms of birth control have different potential side effects. Not all, or even most, users will experience side effects from a method. The less effective the method, the greater the risk of the side effects associated with pregnancy. Minimal or no other side effects are possible with coitus interruptus, fertility awareness-based, and LAM. Some forms of periodic abstinence encourage examination of the cervix; insertion of the fingers into the vagina to perform this examination may cause changes in the vaginal environment. Following the rules for LAM may delay a woman's first post-partum menstruation beyond what would be expected from different breastfeeding practices. Barrier methods have a risk of allergic reactions. Users sensitive to latex may use barriers made of less allergenic materials - polyurethane condoms, or silicone diaphragms, for example. Barrier methods are also often combined with spermicides, which have possible side effects of genital irritation, vaginal infection, and urinary tract infection. Sterilization procedures are generally considered to