Some drugs should be taken on an empty stomach because they need to work fast and are more quickly absorbed - while some will only work on an empty stomach as they can bind with food and form a compound that your body cannot absorb. However, several must be taken with food to reduce the risk of side effects, to slow down absorption, or because they can irritate the stomach,
Before breakfast
- Depression meds: disrupted sleep is a common side effect of some selective serotonin re-uptake inhibitors (SSRIs), so it is often recommended that patients take them when they wake up.
- Osteoporosis meds: your body does not easily absorb biphosphonate drugs (e.g. Boniva and Fosamax), so doctors advice taking them on an empty stomach first thing in the morning with a glass of water, then waiting an hour before eating, drinking, or taking other drugs or supplements.
- Antibiotics are usually most effective when taken on an empty stomach when they are not competing with digestion. But some need to be taken with food to help drug absorption, so check first.
- Diuretics should be taken in the morning so you are not kept awake by night-time toilet trips.
- Thyroid hormones taken at this time fit into your body's natural pattern - but should be taken about an hour before eating as food reduces absorption.
- Iron is always best on an empty stomach as food inhibits absorption. However, vitamin C can help absorption so take with a small glass of orange juice.
- Once-daily PPI medicines (proton pump inhibitors) for heartburn or indigestion (e.g. omeprazole) should be taken on an empty stomach before breakfast to reduce acid-production effectively. But H2-receptor blockers (e.g. ranitidine) also inhibit acid production but should be taken after meals.
- Steroids are best taken in the morning when you are naturally more alert, but take them after breakfast to reduce stomach irritation and indigestion.
- Multi-vitamins are best taken after breakfast, as the fat in the meal helps with the absorption of fat soluble vitamins A, D, E and K.
- Take probiotics after breakfast because an empty stomach is too acidic for friendly bacteria to survive. Eating increases the pH in your gut, enabling the friendly bacteria to thrive. But don't wash them down with tea or coffee - hot drinks can kill healthy bacteria.
- Although different diabetes medicines need to be taken at various times of the day (e.g. sulphonyylureas, including gliclazide, should be taken with breakfast), the biguanides (e.g. metformin) can be taken at any time of day but must be taken with or just after food to avoid low blood sugar levels.
- Prescription or over-the-counter decongestant medicine is most effective taken in the morning when symptoms are naturally worse. They also contain a stimulant that may cause sleeplessness.
- Asthma sufferers whose symptoms are worse at night should consider taking a single dose of inhaled steroid in the afternoon to provide a protective night-time effect.
- BUT as a rule, steroid preventer inhalers (brown canisters) are best taken in the morning and evening.
- Reliever inhalers (blue canisters) are best taken 20 minutes before known triggers, such as exercise. This gives the medication plenty of time to kick in and help prevent an attack.
- Heartburn meds: the stomach produces two to three times more acid between 10pm and 2am than at any other time of day. If you are on an acid-reducing H2 medication such at Pepcid or Zantac, take it 30 minutes before dinner. This controls stomach acid during the overnight period, when secretion reaches its peak.
- Allergy meds: hay fever typically worsens at night and feels most severe in the morning, when levels of symptom-triggering histamine are highest. Once daily antihistamines (e.g Clarityn) reach their peak eight to 12 hours after you take them, so using them at dinnertime means better control of morning symptoms. (Take twice a day antihistamines in the morning and evening.)
- Liquid heartburn medications such as Gaviscon are best taken after meals so they sit on top of stomach contents and coat the gullet to help prevent reflux and indigestion.
- If you have morning stiffness and pain with arthritis, take your later dose of anti-inflammatory painkiller after your evening meal to help when you wake in the morning.
- Cholesterol meds: cholesterol production in the liver is highest after midnight and lowest during the morning and early afternoon, so statins are most effective when taken just before bedtime. The exception to this is atorvastatin which has a longer half life, so even if it is taken in the morning, it remains active through the night.
- Blood pressure meds: blood pressure is typically higher in the day and lower during sleep. Many people with high blood pressure don't show this dip, especially as they get older. This is a risk factor for stroke, heart attack, and kidney disease. So experts advise taking certain blood pressure lowering drugs at bedtime to normalize daily blood pressure rhythm and decrease these risks. ACE inhibitors and ARBs are most effective when taken before bed.
- One-a-day antihistamines for hay fever are most effective if taken in the evening, as this means medication is at its peak in your system in the morning when symptoms are usually worse. (Antihistamines that need to be taken regularly start acting within 15 minutes so can be taken at any time.)
- Osteoarthritis meds: It's best to take NSAIDs (e.g. naproxen and ibuprofen) approximately six hours before pain is at its worst, so they will kick in at the appropriate time. If prone to afternoon pain, take meds between mid-morning and noon; for evening pain, take meds mid-afternoon; for night-time pain, take meds with your evening meal.
1: Actually, there's a right time to take 'once a day' drugs by Claire Benoist in Reader's Digest, 2017
2: Body clock myths: when is the best time to take pills? by Michele O'Connor in The Mirror, 23 July 2014
