Problems with missed doses of medicines

Sometimes people forget to take their medicines at the usual time.

This may cause a problem because missing a dose may make the medicine less effective, but taking doses too close together may increase the risk of side effects.

Here we provide guidance for healthcare professionals on how to advise patients who occasionally forget or are late taking a dose of their medicine(s). The guidance does not apply to patients who frequently miss doses.

Follow these steps to advise patients:

Limitations of our advice

There will be many situations that cannot be covered by general advice such as this, and healthcare professionals should always consider individual circumstances.

Seek further advice

If in doubt, people should seek advice from a pharmacist, doctor or their specialist nurse/clinic.

This is particularly advisable if:

• they have missed more than one day of treatment
• they are taking the medicine less frequently than once a day (e.g. on alternate days, once weekly, monthly) or they are following a less typical dosing regimen
• they are taking certain medicines that need special care or have special instructions (see ‘Advice for Specific Medicines’ below)

Advice for specific medicines

There are many medicines that need special care or have special instructions, and it is not possible to include advice for them all.

Below we give advice for some of the more common medicines people may be taking that would fall into this category.

For all these medicines, the advice still applies to:

• check the Patient Information Leaflet for specific instructions on missed or forgotten doses.
• seek further advice from a pharmacist, doctor or specialist nurse/clinic if there are any concerns or any doubt as to what to do.

Epilepsy medicines

It is especially important for people with epilepsy to take their anti-epileptic medicines regularly. Missing a dose could trigger a seizure, although this would be rare.

People who miss doses should avoid activities where having a seizure could be dangerous.

Where to find advice

Usually people who miss a dose should take the missed dose as soon as they remember unless the next dose is due within a few hours.

An Epilepsy Society website article on Strategies and tools for taking medication recommends that:

• If a medication is usually taken once a day, a forgotten dose should be taken as soon as it is remembered.
• For medicines taken twice a day, a forgotten dose can be taken if it is within 6 hours after it was due (i.e. less than 6 hours late). If the dose is more than 6 hours late, it should be omitted and the next dose taken at the usual time.

Oral contraceptives

Protection against pregnancy may be affected if people miss doses of their oral contraceptive pill.

The advice varies according to:

• the type of oral contraceptive, i.e. combined pill or progestogen only pill (mini-pill),
• how many pills have been missed, and
• when the pills have been missed

Where to find advice

It is safe to follow advice on missed doses in the Patient Information Leaflet supplied with the pill. However this doesn’t necessarily follow official guidance from experts and can sometimes be overly cautious.

For this reason, people should speak to a pharmacist or call 111 or use the 111 online service for advice on missed doses of oral contraceptive pills.

Further information and advice

Alternatively the following organisations provide reliable advice:

• the NHS website Your contraception guide
• the NHS Inform website advice on missed pills.
• FPA the sexual health charity leaflets Your Guide to the Combined pill and Your Guide to the Progestogen-only pill.
• Faculty of Sexual and Reproductive Healthcare Clinical Effectiveness Unit guidance on recommended actions after incorrect use of combined hormonal contraception, including late or missed pills. The rules in this guidance are recognised as being “overcautious”, but “are considered to be simple enough to make them usable in practice”.

Warfarin

Warfarin should be taken as a single dose at the same time each day.

Where to find advice

Advice on missed or forgotten doses in manufacturers’ Patient Information Leaflets (PILs) varies.

Although it is perfectly safe and acceptable to follow the advice in the PIL, people may prefer to follow the pragmatic advice offered in the Warfarin Anticoagulant Record (Yellow Book):

• If you miss a dose and remember before midnight, you can still take that dose.
• If you forget your dose for a longer time, do not take that dose to catch up, but take your next dose when it is due.
• Never take a double dose of warfarin to make up for a missed dose.

Reporting missed doses

People should make a note of any missed doses, preferably in their anticoagulant record book, and remember to tell the healthcare staff at their next blood test appointment.

If they are worried, or have missed more than one dose, they should contact the anticoagulant clinic or their doctor for advice.

Insulin

People with diabetes (type 1 or type 2) will be at risk of high blood glucose (hyperglycaemia), and possibly diabetic ketoacidosis, if they unintentionally miss insulin doses.

Where to find advice

People should follow any specific instructions given by their diabetes nurse/clinic or GP for this scenario. Healthcare professionals should advise people to:

• never take a double dose of insulin to make up for a forgotten dose
• check their blood glucose level, and they may also need to test their urine for ketones, particularly if they have any symptoms
• contact their diabetes nurse/clinic or GP if they have any concerns or need advice on subsequent doses

Methotrexate once-weekly

Doses of once-weekly methotrexate should normally be taken on the same day each week.

Where to find advice

The NHS Methotrexate medicines page gives advice on what to do if people forget to take their tablets.

If a dose is missed, advice depends on when it is remembered:

• Within 2 days: take the forgotten dose now, then take the next dose as normal. For instance, if a person normally takes their methotrexate on a Tuesday, they could take it on Wednesday or Thursday, then take their next dose on Tuesday as normal.
• 3 or more days later: skip the forgotten dose entirely. Take the next dose as scheduled on the usual day.
• Never take a double dose of methotrexate to make up for a missed dose.

People may be reassured that it is unlikely that a disease flare-up would occur as a result of a single missed dose.

Parkinson’s disease medicines

Taking medicines for Parkinson’s disease on time is extremely important for managing Parkinson’s symptoms.

Risks of missed doses

A missed or late dose could mean the patient is unable to move, get out of bed, swallow, walk or talk.

Even a delay of 30 minutes could be serious, with a risk of Neuroleptic Malignant Syndrome (NMS) when medicines for Parkinson’s disease are suddenly stopped.  This is a rare, but serious and potentially fatal reaction. Symptoms include stiffness, muscle twitching, shaking, agitation, confusion, high body temperature (hyperpyrexia), increased heart rate, unstable blood pressure and coma.

People may also experience more Parkinson’s symptoms if they have missed or taken a dose later than usual. This could happen on the same day, or the day after, so they will need to be careful, especially when driving or using machinery.

Where to find advice

A Parkinson’s UK Q&A: The Importance of getting Parkinson’s Medication on Time suggests the following practical advice for people if they forget to take a dose of their medicine(s):

• take the forgotten dose as soon as you remember, and then adjust the time of the next dose. For example, if you normally take doses at 8am, 12pm, 4pm and 8pm, but forget the 12pm dose until 2pm, take it then and adjust your next doses to 6pm and 10pm.
• if taking a once daily medication, you can still take the forgotten dose if you remember on the same day. But, if you don’t remember until the next day, skip that dose.
• do not take two doses together to make up for a forgotten dose or take your late dose really close to your next one

Further information and advice

• Parkinson’s UK website: Get it on Time campaign
• NICE guideline NG71: Parkinson’s disease in adults (section 1.3)
• NICE Quality Standard QS164: Parkinson’s disease (quality statement 4)
• product information (summaries of product characteristics and patient information leaflets) available on the emc website or MHRA products website 

People should contact their Parkinson’s nurse/clinic, pharmacist or GP if they have any concerns about a missed or late dose, or need advice on subsequent doses.

General advice and tips on managing medicines for Parkinson’s disease are available for patients and carers on the Parkinson’s UK website: Managing drug treatments for Parkinson’s.

Bisphosphonates for osteoporosis

Bisphosphonate medicines for treating or preventing osteoporosis (alendronic acid, risedronate, ibandronic acid) have very specific instructions on how and when to take them.

Administration

Bisphosphonate medicines must be taken on an empty stomach, sitting or standing upright, with a full glass of plain water. This is to make sure they work properly and to reduce possible irritation of the oesophagus.

For this reason, the advice is usually to take them shortly after getting up for the day, 30 to 60 minutes before the first food, drink (other than plain water) or other medicines of the day.

Doses of bisphosphonate medicines vary. Alendronic acid and risedronate may be taken once daily or once weekly, while ibandronic acid is taken monthly. For once weekly or monthly dosing, people are advised to stick to a schedule, i.e. same day each week or a certain day each month.

Where to find advice

If they miss or forget a dose, it is important for people to follow the advice in the PIL specific to the bisphosphonate they are taking.

Royal Osteoporosis Society advice on getting the best from your osteoporosis medication reassures people that missing the odd dose is unlikely to affect overall bone health.

The following advice can be offered if a PIL is not available:

Once daily alendronic acid

If you forget to take your dose at your usual time, skip that dose. Take the next dose as usual the next day.

Do not take two doses on the same day.

Once daily risedronate

If you forget to take your dose at your usual time, you can either:

• skip that dose, then take the next dose as usual the next day, or:
• take the missed dose at the next possible time, making sure you take it on an empty stomach. This could be between meals or in the evening, as long as it is at least 2 hours after your last food, drink (other than plain water) or other medicines. You should wait for 2 hours after taking the dose before eating or drinking (other than plain water).

Do not take two doses on the same day.

Once weekly alendronic acid or risedronate

If you forget to take your dose at your usual time, take it the morning after you remember. Do not take the missed dose later that day. Then go back to taking your dose once as week as usual on your chosen day.

Do not take two doses on the same day.

Monthly ibandronic acid

If you forget to take your dose on your chosen day, check when your next scheduled dose is due:

• more than 7 days away: take the missed dose the morning after you remember. Do not take a dose later in the day.
• 7 days or less away: skip the missed dose, and take the next dose as scheduled. Do not take two doses within the same week.

Then continue taking one tablet once a month on the scheduled days as planned.

Immunosuppressant (transplant rejection) therapy and cancer medicines

People should ask their doctor or specialist nurse/clinic for advice on what to do if they have missed a dose of transplant rejection or cancer medicine.

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