Monophasic and Multiphasic Pills

Monophasic pills deliver the same dose of oestrogen and progestin in every active tablet. Multiphasic pills change the dose in two, three or four steps across the active tablets to follow the natural cycle more closely and to lower the total progestin dose. Both groups suppress ovulation, thicken cervical mucus and share the same eligibility categories, warning signs and failure rates.

Types and examples.

Effectiveness. First-year pregnancies: 8 in 100 women with typical use and 0.3 in 100 with perfect use for pills as a class. Comparative studies show no consistent difference in contraceptive efficacy, cycle control or continuation between monophasic and multiphasic pills.

Return to fertility. Without delay after stopping.

Packaging. Active tablets of a multiphasic pack differ in colour and are taken in order. Monophasic active tablets are identical, so any active tablet can fill a missed day.

Selection. A monophasic pill is the usual first choice. It is required for extended and continuous regimens, because every active tablet must be identical, and it allows simpler missed-pill instruction. A multiphasic pill suits a patient who is established on it with good bleeding control, or a patient who prefers it after counselling that benefit is unproven.

Eligibility. Categories are those of every combined pill.

• Category 4: breastfeeding under 6 weeks; blood pressure 160/100 or more; ischaemic heart disease, stroke or complicated valvular disease; migraine with aura; current or past breast cancer; current or past deep vein thrombosis or pulmonary embolism; thrombogenic mutation; lupus with positive or unknown antiphospholipid antibodies; smoker 35 years or more with 15 or more cigarettes daily; decompensated cirrhosis; liver adenoma or malignancy; diabetes with vascular disease.
• Category 3: rifampicin, rifabutin and enzyme-inducing antiseizure medicines.

Investigations. Blood pressure and body mass index only. No routine laboratory tests.

Counselling points for the clinician. State that multiphasic dosing has not been shown to give better safety, efficacy or bleeding control. Explain that in a multiphasic pack the position of each tablet matters and that the pack must be started with the first tablet in sequence.

Regimen line. Oral, one tablet daily at about the same time, in pack order for multiphasic products. Monophasic and triphasic packs hold 21 active tablets followed by 7 hormone-free days or 7 inactive tablets; the four-phase pack holds 26 active and 2 inactive tablets. Start within 5 days of the start of menses with no backup; later starts need 7 days of backup. Grace: missing 1 or 2 pills carries little or no risk.

Backup 7 days after 3 or more missed pills. Enzyme inducers: do not use. Adjust for postpartum, breastfeeding, age 40 years or more (category 2) and liver disease using the usual combined pill rules.

Missed pills. Missed 1 or 2 pills: take the missed tablet as soon as possible and continue in pack order; no backup.

Missed 3 or more in week 1 or 2: take the next tablet now, continue in order, backup 7 days, consider emergency contraception if sex in the last 5 days.

Missed 3 or more in week 3: finish the active tablets, discard the inactive tablets, start the next pack the next day, backup 7 days, consider emergency contraception.

Vomiting within 2 hours: take another tablet. Vomiting or diarrhoea for more than 2 days: apply the rule for 3 or more missed pills.

Switching. Between monophasic and multiphasic pills no gap is needed: start the new pack the day after the last active tablet of the old pack, or after the usual hormone-free interval. No backup is needed if the old pill was taken correctly. From other hormonal methods used correctly, start at once; from an injectable, start when the next dose is due.

Postpartum and breastfeeding. Not breastfeeding: not before 21 days. Breastfeeding: from 6 months; between 6 weeks and 6 months generally avoided.

Follow up. Review at about 3 months and then yearly: blood pressure, weight, smoking, medicines and bleeding.

Expected effects. Spotting and irregular bleeding in the first 3 months, nausea, breast tenderness, headache. Some comparisons show more unscheduled bleeding in multiphasic pills, but evidence is mixed.

Management of unscheduled bleeding. Exclude pregnancy, infection, missed pills and interactions. Reinforce timing. If persistent after 3 months, switch to a monophasic pill with a different progestin or a higher ethinylestradiol dose. Ibuprofen 800 mg orally three times daily for 5 days with food gives short-term relief (maximum 2.4 g daily; avoid in renal impairment, active peptic ulcer or significant liver disease; not used in pregnancy).

Serious complications and red flags. Venous thromboembolism, stroke, myocardial infarction; severe abdominal pain, chest pain or breathlessness, severe headache, eye problems and severe calf pain. Stop and refer urgently.

When to change method. Category 4 conditions, migraine with aura, enzyme-inducing medicines, or unacceptable bleeding after a change of formulation.