Risedronate (Risedronate Sodium): How to Take It, Side Effects and How It Compares with Alendronic Acid

Risedronate (risedronate sodium, brand name Actonel) is a bisphosphonate tablet for osteoporosis, most often taken as one 35mg tablet once a week, or 5mg once a day. It slows bone breakdown and lowers the risk of fractures. The key is how you take it: first thing in the morning on an empty stomach, with a full glass of plain water, staying upright and taking nothing else for at least 30 minutes.

What is risedronate?

Risedronate is a bisphosphonate, the family of first-line osteoporosis medicines that protect bone by slowing the cells that break it down. "Risedronate", "risedronate sodium" and "risedronic acid" are names for the same medicine; Actonel is the original brand, and generic tablets are widely prescribed.

The UK product information lists three uses: post-menopausal osteoporosis, to reduce the risk of spine fractures; established post-menopausal osteoporosis, to reduce the risk of hip fractures; and osteoporosis in men at high risk of fractures emc, risedronate 35mg SmPC. The Royal Osteoporosis Society (ROS) adds that doctors occasionally offer it to younger women Royal Osteoporosis Society. For how it sits alongside the other drugs in the class, see bisphosphonates for osteoporosis.

How do you take risedronate?

Take the weekly 35mg tablet on the same day each week, as soon as you get up, before any food, drink or other medicine. The product information sets out the routine emc, risedronate 35mg SmPC:

1. Empty stomach. Take it at least 30 minutes before the first food, drink (other than plain water) or other medicine of the day.
2. Plain water. Swallow it with a glass of plain water (at least 120ml). The ROS specifies plain tap water.
3. Swallow it whole. Do not suck or chew it.
4. Stay upright. Sit or stand, and do not lie down, for 30 minutes afterwards.

Calcium is a common trip-up. The ROS says to take calcium supplements at least half an hour after risedronate, and some doctors suggest waiting up to four hours Royal Osteoporosis Society. If you take a combined calcium and vitamin D tablet, ask your pharmacist about the best time of day.

Weekly or daily risedronate: what is the difference?

The 35mg weekly tablet and the 5mg daily tablet do the same job; the weekly one simply means you follow the routine once a week instead of every day. The ROS lists both strengths. One advantage of the daily tablet is a little flexibility: if you cannot take it in the morning, the ROS says you can take it later in the day, but only if you have had nothing except plain tap water for two hours before and two hours after Royal Osteoporosis Society. Most people find the weekly tablet easier.

What if you miss a dose?

If you forget your weekly tablet, the ROS says to wait until the next morning to take it, then go back to your usual day the following week. The product information says to take one tablet on the day it is remembered and return to your normal day, and stresses that two tablets should not be taken on the same day. Either way, follow the empty-stomach rules when you take it.

Who should not take risedronate?

Risedronate is not suitable if you have low blood calcium, severe kidney problems, or are pregnant or breastfeeding. The product information lists these as contraindications, with severe kidney impairment defined as a creatinine clearance below 30 ml/min. Low calcium (hypocalcaemia) has to be corrected before starting emc, risedronate 35mg SmPC.

The ROS adds that it may not suit you if you cannot swallow tablets, have a gullet problem such as Barrett's oesophagus, or cannot stay sitting or standing upright for at least 30 minutes Royal Osteoporosis Society. The product information also urges caution in people with a narrowed gullet, achalasia or recent stomach or gullet problems.

What are the side effects of risedronate?

Most side effects of risedronate are mild and stomach-related, and many are no more common than with a dummy tablet in trials. In the product information's trial data, constipation (5.0% vs 4.8% on placebo), indigestion (4.5% vs 4.1%) and nausea (4.3% vs 4.0%) were reported at similar rates on risedronate and placebo. Headache, tummy pain, diarrhoea and musculoskeletal pain are also listed as common emc, risedronate 35mg SmPC.

The ROS gives this overview Royal Osteoporosis Society:

• Inflamed gullet, sore throat, difficulty swallowing or heartburn: fewer than 1 in 10. A full glass of water and staying upright help. Tell your doctor if it does not settle.
• Bone, joint or muscle pain: fewer than 1 in 10, often improving as your body adjusts. Paracetamol may help.
• Headache: fewer than 1 in 50.
• Eye inflammation (pain or blurred vision): fewer than 1 in 100. See a doctor promptly for a painful red eye.
• Atypical thigh bone fracture: fewer than 1 in 1,000, usually after many years. Report new thigh, hip or groin pain.
• Osteonecrosis of the jaw: fewer than 1 in 1,000, usually after major dental work. Keep up good oral hygiene and regular dental check-ups, and tell your dentist you take risedronate.

If side effects persist, tell your doctor or pharmacist rather than stopping. Another medicine may be the cause, or a different bone treatment may suit you better.

How does risedronate compare with alendronic acid?

Risedronate and alendronic acid are close cousins: both are weekly bisphosphonate tablets taken on an empty stomach with plain water, followed by 30 minutes upright. The ROS says alendronate "is usually the first medicine that people are offered" for osteoporosis, although this may differ for you Royal Osteoporosis Society. Risedronate is a common alternative if alendronic acid does not suit you.

	Risedronate	Alendronic acid
Usual dose	35mg weekly or 5mg daily	70mg weekly
Wait before food or drink	At least 30 minutes	At least 30 minutes
Typical first review	About 5 years	About 5 years
Reassess after stopping (NOGG)	18 months	2 years

One practical difference shows up after a planned treatment pause. UK guidance from the National Osteoporosis Guideline Group (NOGG) recommends reassessing fracture risk 18 months after stopping risedronate, compared with two years after stopping alendronate NOGG. For alendronic acid, the UK product information for Fosamax gives a 70mg once-weekly dose taken with plain water at least 30 minutes before the first food, drink or medicine, without lying down for 30 minutes emc, Fosamax SmPC. Read more in our guide to alendronic acid side effects.

If tablets are not suitable at all, options include a once-a-year zoledronic acid infusion, monthly or three-monthly ibandronic acid, six-monthly denosumab (Prolia), or, for very high risk, a bone-building drug such as teriparatide. Our osteoporosis treatment guide explains how doctors choose.

How long do you take risedronate for?

Plan on at least five years before a formal review. NOGG makes a strong recommendation to plan oral bisphosphonates, including risedronate, for at least five years, and for at least ten years for some higher-risk people, such as those aged 70 or over when they started or with a previous hip or spine fracture NOGG.

The ROS says check-ins usually happen about three months and one year after starting, with a formal review after about five years. Options then include continuing, a treatment pause of one or two years if it is safe for you, switching or stopping. Risedronate may keep helping for about one to two years after you stop Royal Osteoporosis Society.

How can you keep an eye on your bones while on risedronate?

Your GP reviews your fracture risk over time and may arrange a repeat DXA scan at review, because bone density changes slowly. Calcium, vitamin D and regular weight-bearing exercise all help the medicine work. For an extra check between appointments, some people book a Screen My Bones bone health assessment, which uses radiation-free REMS ultrasound and can be repeated for monitoring. It does not replace DXA for diagnosis or NHS treatment decisions. Keep taking risedronate as prescribed, and talk to your doctor before making any change.

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This article is part of our bone health series. It is general information, not a substitute for advice from your own doctor or pharmacist.