Food and drug interactions (2022)

There are various foods, drugs and supplements that can cause problems for the thyroid and for people taking thyroid hormone replacements. You need to be aware of these food and drug interactions and ensure that you either take them a few hours away from taking your thyroid medication or make sure that, if they decrease your levels, you increase your dosage. Make sure you have regular thyroid function tests if you start taking any new drugs or supplements and be guided by your clinician.

Please follow the advice of your clinician or pharmacist and especially before stopping any medication because of suspected food and drug interactions.

Foods that can cause problems

Goitrogenic foods

Goitrogenic foods can act like an antithyroid drug in disabling the thyroid function. They prevent the thyroid from using available iodine. It is made worse if you use a lot of salt because that causes the thyroid to swell.Do not eat these in large amounts if you are taking thyroid hormone replacement.It is thought that the enzymes involved in the formation of goitrogenic materials in plants can be destroyed by cooking, so cook these foods thoroughly if you want to eat them:

  • Brussels sprouts, rutabaga, turnip, cauliflower, cabbage and kale
  • almonds, peanuts and walnuts
  • sweetcorn, sorghum and millet
  • raw swede, turnip and kale

Soya

There is still debate over whether soya interferes with absorption of levothyroxine. Some studies have shown no effect and some have shown an effect on women. Therefore, it may be prudent to not eat soya near the taking of your levothyroxine . Leaving a gap of four hours should ensure that it doesn’t interfere with your medication.

Fibre

Too much dietary fibre can affect the absorption of your levothyroxine so try to eat any fibrous foods away from the time you take your thyroid medication.

Kelp

Kelp comes from seaweed and is naturally high in iodine . Kelp can therefore interfere with thyroid function. Although iodine is needed to make thyroxine and causes problems if you are deficient, those who are not deficient have no need to take it. If you take more iodine than you need it can cause problems for the thyroid such asoveractivity. It can also have the opposite effect and make you more hypothyroid.

(Video) Food & Drug Interactions: Which Ones to Avoid

Coffee

Coffee can interfere with absorption of levothyroxine so do not take your levothyroxine at the same time as drinking coffee – it’s probably best to wait at least an hour before partaking in your morning cup of coffee

Supplements that can stop the absorption of levothyroxine

Calcium

Some calcium -rich foods and supplements interfere with levothyroxine absorption. A gap of 4 hours between the two would be adequate to ensure there is no significant impact on blood thyroxine levels. If you are trying to lose weight and use lower fat milk (i.e. semi-skimmed or skimmed), this remains high in calcium despite being lower in fat.

Iron

Iron tablets (ferrous sulphate) can interfere with the absorption of levothyroxine. It’s best to wait two hours before taking your iron tablets. Be aware that some multivitamins may contain calcium and iron.

Drug interactions

Medicines that can strain your thyroid

Any of the following can interfere with the smooth working of the gland, or at least upset the tests:

  • tolbutamide (Rastinon), for diabetes
  • chlorpropamide (Diabinese), also for diabetes
  • phenylbutazone (Butacote) for ankylosing spondylitis
  • diazepam (Valium) for anxiety
  • heparin, to prevent clotting in heart problems. (NB: Blood thinning drugs like warfarin, Coumadin or Heparin can on occasion become stronger in the system when thyroid hormone is added to the mix.)
  • lithium (Priadel) to prevent relapse in psychiatric illness. More than a third of people taking lithium develop an underactive thyroid
  • beta blockers (e.g. Propranolol, Inderal) for high blood pressure
  • salicylates , including aspirin (e.g. Disprin), a pain killer
  • steroids (e.g. prednisolone) for any severe physical reaction
  • phenothiazines (e.g. Largactil) major tranquillisers
  • amiloride (e.g. Moduretic) a water tablet
  • androgens (e.g. testosterone) male sex hormone
  • tamoxifen , an anti-oestrogen to ward off breast cancer
  • sulphonamides, anti-bacterial drugs
  • acetazolamide (Diamox) for glaucoma and fluid retention
  • resorcinol (Anusol) used for piles
  • PAS for tuberculosis
  • prochlorperazine (Stemetil) for nausea and vomiting

All of these medicines suppress thyroid activity, so that the level of T4 in the blood is low, even if the gland is perfectly healthy. Sometimes, particularly with lithium, Hashimoto’s disease develops.

Drugs that affect the absorption of levothyroxine

  • ciprofloxacin – an antibiotic
  • antacids – most of these contain aluminium hydroxide and is well known for reducing the body’s ability to absorb thyroxine.
  • laxatives
  • colestipol – a cholesterol lowering drug
  • colestyramine – a cholesterol lowering drug
  • sulcralfate – used to treat ulcers and other gastrointestinal problems
  • raloxifene – given for postmenopausal osteoporosis
  • Proton pump inhibitors – given for esophageal reflux disease (GERD) and stomach ulcers to lower stomach acid levels
  • Orlistat (Xenical) – given for weight loss

The following medicines have a different effect

  • Phenytoin and related medicines – these anticonvulsants, used to control epilepsy, use up the thyroid hormones unusually quickly, and this may cause a shortage
  • Phenobarbital and Carbamazepine – can accelerate the degradation and increase the dose requirement for L-T4
  • Diphenylhydantoin may interfere with thyroxine binding to proteins and thereby reduce T4 levels
  • Valproic acid – causes an increase in TSH levels in children (subclinical hypothyroidism )
  • Carbamazepine (Tegretol) – this anticonvulsant inhibits the release of T4 into the blood
  • Co-trimoxazole (Septrin) – for urinary infections – also inhibits the release of T4 into the blood
  • Levodopa (Sinemet) and bromocriptine (Parlodel) are both used for Parkinson’s disease and both stop the stimulating action of TSH, leading to less T4 and T3
  • Adrenaline Anaesthetic used by dentists

Medicines that seem to increase T4 and T3

Note that neither of these drugs actually stimulates the production of more hormones.

(Video) Food Drug Interactions

  • Frusemide-type water tablets (e.g. Lasix) by getting rid of fluid, make the blood more concentrated so there is more of the hormones per millilitre
  • Oestrogen (in the contraceptive pill and HRT), provides more of the transport protein making the hormone inactive. Any oestrogen raises the levels although thyroid activity is unchanged. This could make your levels look within the normal range, whereas they are really below it.After starting on any oestrogen therapy, a woman should always have TSH tested to see if the oestrogen is having an impact on overall TSH and thyroid function and may require a dosage adjustment

Medicines containing iodine

Be wary of these if you have ever had a thyroid problem, and think if it could be your thyroid if you get some puzzling symptoms when you are taking one of them. These medicines are liable to give your thyroid more iodine than it can cope with. It may react by going into overdrive and producing too much hormone, with anxiety and palpitations in consequence, especially to start with. The usual end result, however, is near-complete downing of tools by the gland so that it runs into obvious underactivity, and general bodily slowing up.

  • Amiodarine (Cordarone X) is an excellent medicine for tricky faults in the rhythm of the heart, but it causes thyroid problems in 6% of people taking it. These may be due to either under or overactivity, with totally different symptoms: snail-pace or edgy speed. Since it takes a long time to clear Amiodarone from the circulation, and anyway it may be vital for the heart, it is usually best to continue with it, but help the thyroid with other drugs. These will be thyroxine in the case of underactivity, or an antithyroid such as Carbimazole in the opposite situation
  • Cough medicines containing iodides including over the counter preparations are not for you if you’ve ever had a thyroid problem
  • X-ray contrast media given, for instance, for gall-bladder investigation.
  • Povidone skin antiseptic (Betadine) and tincture of iodine.Very little iodine is likely to get into the system from these but they should be avoided during pregnancy
  • Multivitamin/multimineral supplements

Salicylates

Salicylate is a term used to describe a group of drugs that are chemically related to salicylic acid, which is a simple, single-ringed organic molecule that occurs naturally as a component of salicylin (a glucoside found in Willow Bark) and methyl salicylate (in Oil of Wintergreen).These natural products are usually used in the treatment of rheumatism.However, in 1899 the semi synthetic drug Acetylsalicylic acid was introduced under the name Aspirin.

Salicylates can cause various metabolic changes such as changes in acid-base balance and electrolyte balance, which can, in turn, alter blood pressure and heart rate. However, mechanism of action seems to be as follows in respect of the thyroid hormones.

Thyroxine hormone binds to certain hormones in the blood called TBG Proteins. However, thyroxine can be displaced from TBG Proteins by certain substances such as drugs. In addition, if the amount of TBG Protein changes, this will alter the amount of thyroxine in the blood.

Some products used to treat acne and skin disorders contain Salicylates, but since these are used topically as are Oil of Wintergreen (typically found in Relax, Deep Heat etc.) we do not know what effects these have on the thyroid.

Drugs Containing Salicylates

  • Aspirin (acetylsalicylic acid)
  • Salicylic acid
  • Methyl Salicylate (Oil of Wintergreen)
  • Sodium Salicylate
  • Diflunisal

Other Drug and Chemical interactions

  • Prempak C/Premanin etc – HRT made from mares urine that interferes with thyroid availability
  • Amiodarone hydrocholoride – this is an anti-arrythmic and should not be given to patients with thyroid disorders. If you are on this drug you should be regularly tested for thyroid disease
  • Insulin and similar oral hypoglycaemic drugs – given for diabetes, this can reduce the effectiveness of thyroid hormone. Be sure your doctor knows you are on one before prescribing the other. If you are on insulin or an oral hypoglycaemic, you should be closely watched during the initiation of thyroid replacement hormone
  • Cholesterol-Lowering drugs (statins) – these drugs bind thyroid hormones, and a minimum of four to five hours should elapse between taking these drugs and thyroid hormones
  • Oxymetazoline Hydrochloride – a sympathomimetic, an alpha-adrenoreceptor stimulant used in nasal decongestants. This drug works indirectly through the release of Noradrenaline from sympathetic nerve endings. This drug should have a warning on to administer with caution to patients with heart, kidney and thyroid disorders, diabetes and hypertension
  • Dihydrocodeine Tartrate – an analgesic for the relief of moderate to severe pain. Should only be given in reduced dosages to people with hypothyroidism

For more support check out our online community:

http://www.healthunlocked.com/thyroiduk

(Video) Drug Interactions - HealthConnection Talk

Date updated: 23/08/21 (V1.4)
Review date: 09/04/22

We rely on donations so that we can continue to supportand campaignforpeople with thyroid and related conditions.If you have found our information helpful, please make a donation or become a member.

MAKE A DONATION

(Video) When Food and Drugs Collide: Food and Drug Interactions

FAQs

What is drug-food interaction? ›

Drug-food interaction: A reaction between a drug and a food or beverage. Drug-condition interaction: A reaction that occurs when taking a drug while having a certain medical condition. For example, taking a nasal decongestant if you have high blood pressure may cause an unwanted reaction.

Why are food and drug interactions important? ›

Regarding food-drug interactions physicians and pharmacists recognize that some foods and drugs, when taken simultaneously, can alter the body's ability to utilize a particular food or drug, or cause serious side effects.

Does food interfere with medication? ›

Food-medicine interactions can happen with both prescription and over-the-counter (OTC) medicines. These include antacids, vitamins, iron pills, herbs, supplements, and beverages. Some nutrients can affect the way you metabolize certain medicines by binding with the medicine's ingredients.

Which is the most common type of drug interaction? ›

pharmacokinetic – defined as an alteration in the absorption, distribution, metabolism or excretion of one drug by another. This is the most common type of drug interaction.

What fruits interact with drugs? ›

Fruit Interactions with Common Medicines
  • Medicines can interact with whole fruit, fruit pulp or fruit extracts.
  • Fruit of concern include orange, pomelo, pomegranate, cranberry, red/purple grape, apple, and grapefruit.
  • Patients should be informed about the risk of interactions from consuming fruit.
5 Mar 2015

Which drug should not be taken with milk? ›

The milk interferes with the absorption of various antibiotics such as tetracycline's (decreasing absorption) and few quinolones, propranolol, mercaptopurine (reduce bioavailability), nonsteroidal anti-inflammatory drugs, digitalis, amiloride, omeprazole, spironolactone and ranitidine.

Which factors that affect food and drug interaction? ›

According to the findings of the present study, the age, number of medications, and duration of disease were the most important factors significantly associated with higher risk for potential food-drug interactions in hospitalized patients admitted to the Department of Internal Medicine.

How do you manage drug interactions? ›

Minimizing the risk of interactions
  1. Know why you are taking each medication. ...
  2. Know how to take the drug. ...
  3. Fill all your prescriptions at the same pharmacy. ...
  4. Be suspicious of supplements. ...
  5. Go easy on grapefruit juice. ...
  6. Limit alcohol. ...
  7. Talk to your pharmacist.
10 May 2016

What medications Cannot be taken together? ›

Specifically, drugs that slow down breathing rate, such as opioids, alcohol, antihistamines, CNS depressants, or general anesthetics, should not be taken together because these combinations increase the risk of life-threatening respiratory depression.

Why are some drugs absorbed better with food? ›

Absorption of medicines from the gut

Certain medicines are recommended to be given with food because the physiological changes after eating can increase the amount of medicine absorbed by the body.

Is a piece of bread enough to take medicine? ›

Eat neutral foods

Crackers, rice, bread, peanut butter, and other neutral foods do a good job coating your stomach and prompting digestion, which helps your body to metabolize your medication efficiently.

What is the best drug interaction checker? ›

Is there a reliable website FDA recommends? Try the websites www.drugs.com/fda-consumer/ or MedlinePlus. Drugs.com is designed for both consumers and health professionals.

Can you take 2 medications at the same time? ›

There are many types of drugs you shouldn't take together, but in general, don't take combinations like these: Two or more drugs that share an active ingredient. You could have side effects or an overdose. Active ingredients are the chemicals in medications that treat your condition or symptoms.

What's best for inflammation? ›

Ibuprofen (Advil, Motrin) and Naproxen (Aleve).

“In general, pain that is associated with inflammation, like swelling or acute injury, is better treated with ibuprofen or naproxen,” says Matthew Sutton, MD, a Family Medicine physician at The Iowa Clinic's West Des Moines campus.

What are two drug interactions called? ›

Listen to pronunciation. (SIH-ner-JIS-tik) In medicine, describes the interaction of two or more drugs when their combined effect is greater than the sum of the effects seen when each drug is given alone.

What are symptoms of drug interactions? ›

Symptoms of adverse drug reactions include:
  • skin rash.
  • bruising.
  • bleeding.
  • swelling.
  • dizziness.
  • severe nausea and vomiting.
  • diarrhea.
  • constipation.
1 Sept 2000

What is it called when two medications interact badly? ›

Drug-drug interactions occur when two or more drugs react with each other. This drug-drug interaction may cause you to experience an unexpected side effect.

Do bananas interfere with any medications? ›

5. Bananas and other potassium-rich foods, plus ACE inhibitors. If you take blood pressure-lowering ACE inhibitors with potassium-rich foods, including bananas, avocados, tomatoes and dried apricots, you can get high potassium levels in your body, which can lead to potentially dangerous heart arrhythmias, Brown warns.

How long after eating is your stomach empty for medication? ›

As a general rule, medicines that are supposed to be taken on an empty stomach should be taken about an hour before a meal, or 2 hours after a meal. Forgetting these instructions on rare occasions is unlikely to do any harm, but taking these medicines with food regularly may mean they don't work.

Which drugs should be taken with food? ›

Some medicines need to be taken with or after food.
...
To reduce side effects of stomach irritation, including indigestion, stomach inflammation or ulcers
  • aspirin.
  • non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac and ibuprofen.
  • steroids, such as prednisolone and dexamethasone.

Who should avoid bananas? ›

You shouldn't eat them if you're taking certain medications.

Two types of medication that you should avoid eating bananas with are ACE inhibitors (such as lisinopril, enalapril, or ramipril) and spironolactone. That's because they raise blood potassium levels, according to Harvard Medical School.

Does oatmeal interfere with medications? ›

Soluble fiber and gelling agents can pose similar problems. Soluble fiber is the kind found in oatmeal and in fiber supplements such as psyllium. It forms a sticky gel in the presence of moisture, which immobilizes nutrients -- and medications -- in your digestive system and slows their absorption.

Do blueberries interact with medications? ›

Blueberry fruit or leaf might lower blood sugar levels. Taking blueberry along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.

Does chocolate interfere with medications? ›

Chocolate. Dark chocolate in particular can weaken the effects of drugs meant to calm you down or make you sleep, like zolpidem tartrate (Ambien). It also can boost the power of some stimulant drugs, like methylphenidate (Ritalin).

How long should I wait to drink milk after taking medicine? ›

“You need to leave a window either side of taking the antibiotic — avoid milk and other dairy products, such as ice cream, custard or cheese, for two hours before and afterwards.

Is it OK to drink milk after taking medicine? ›

Dairy products, antacids, and iron preparations prevent some medications from being properly absorbed into the body. If the medication is not properly absorbed, it may be less effective.

Which drugs should be taken with food? ›

Medications which should be Taken with FOOD
Allopurinol (take after meal)Atovaquone (Mepron)Augmentin
Amiodarone (Cordarone)Baclofen (Lioresal)Bromocriptine (Parlodel)
Carvedilol (Coreg)Carbamazepine (Tegretol)Chloroquine
Cefpodoxime (Vantin)Diclofenac (Voltaren_Divalproex sodium (Depakote)
12 more rows
1 Sept 2017

What fruits interact with drugs? ›

Fruit Interactions with Common Medicines
  • Medicines can interact with whole fruit, fruit pulp or fruit extracts.
  • Fruit of concern include orange, pomelo, pomegranate, cranberry, red/purple grape, apple, and grapefruit.
  • Patients should be informed about the risk of interactions from consuming fruit.
5 Mar 2015

What should you avoid while taking methotrexate? ›

There are no specific foods that you need to avoid while taking methotrexate. However, methotrexate may reduce your ability to fight infection. Therefore, it's best to avoid unpasteurised milk and soft cheeses.

Which drugs should not be taken with milk? ›

Results. The milk interferes with the absorption of various antibiotics such as tetracycline's (decreasing absorption) and few quinolones, propranolol, mercaptopurine (reduce bioavailability), nonsteroidal anti-inflammatory drugs, digitalis, amiloride, omeprazole, spironolactone and ranitidine.

How do I coat my stomach before medication? ›

Eat neutral foods

Crackers, rice, bread, peanut butter, and other neutral foods do a good job coating your stomach and prompting digestion, which helps your body to metabolize your medication efficiently.

How long after eating is your stomach empty for medication? ›

As a general rule, medicines that are supposed to be taken on an empty stomach should be taken about an hour before a meal, or 2 hours after a meal. Forgetting these instructions on rare occasions is unlikely to do any harm, but taking these medicines with food regularly may mean they don't work.

Which drugs should be taken on an empty stomach? ›

Medications that should be taken on an empty stomach include:
  • ampicillin.
  • bisacodyl.
  • cloxacillin.
  • didanosine.
  • etidronate.
  • risedronate.
  • sotalol.
  • sucralfate.

Do bananas interfere with any medications? ›

5. Bananas and other potassium-rich foods, plus ACE inhibitors. If you take blood pressure-lowering ACE inhibitors with potassium-rich foods, including bananas, avocados, tomatoes and dried apricots, you can get high potassium levels in your body, which can lead to potentially dangerous heart arrhythmias, Brown warns.

Who should avoid bananas? ›

You shouldn't eat them if you're taking certain medications.

Two types of medication that you should avoid eating bananas with are ACE inhibitors (such as lisinopril, enalapril, or ramipril) and spironolactone. That's because they raise blood potassium levels, according to Harvard Medical School.

Does oatmeal interfere with medications? ›

Soluble fiber and gelling agents can pose similar problems. Soluble fiber is the kind found in oatmeal and in fiber supplements such as psyllium. It forms a sticky gel in the presence of moisture, which immobilizes nutrients -- and medications -- in your digestive system and slows their absorption.

Why is methotrexate so toxic? ›

It is generally considered to be safe and therefore, it is not unusual to prescribe doses as high as 25 to 30 mg per week in modern rheumatology [6, 7]. Methotrexate toxicity is mainly due to its effects on folate metabolism.

Why can you not touch methotrexate? ›

Even touching or inhaling the dust from the tablet can allow the medicine to get into the body. Methotrexate goes into sperm, so it's important that a man taking it doesn't get his partner pregnant. Whether you're male or female, you must use birth control while taking methotrexate.

What are the worst side effects of methotrexate? ›

Methotrexate may cause serious or life-threatening skin reactions. If you experience any of the following symptoms, call your doctor immediately: fever, rash, blisters, or peeling skin. Methotrexate may decrease the activity of your immune system, and you may develop serious infections.

Does chocolate interfere with medications? ›

Chocolate. Dark chocolate in particular can weaken the effects of drugs meant to calm you down or make you sleep, like zolpidem tartrate (Ambien). It also can boost the power of some stimulant drugs, like methylphenidate (Ritalin).

How long should I wait to drink milk after taking medicine? ›

“You need to leave a window either side of taking the antibiotic — avoid milk and other dairy products, such as ice cream, custard or cheese, for two hours before and afterwards.

What medications Cannot be taken together? ›

Specifically, drugs that slow down breathing rate, such as opioids, alcohol, antihistamines, CNS depressants, or general anesthetics, should not be taken together because these combinations increase the risk of life-threatening respiratory depression.

Videos

1. Food Drug Interaction
(LSU Health Shreveport)
2. Drug interactions: Foods as dangerous as grapefruits?
(CBS News)
3. Common Drug Food Interactions
(Pharmacist Conversations)
4. Food & Drug Interations
(Apollo Hospitals)
5. Drug Interactions - Types
(Sajid Majeed)
6. Common Drug-Food Interactions
(UConn Pharmacy)

Top Articles

Latest Posts

Article information

Author: Corie Satterfield

Last Updated: 12/02/2022

Views: 5349

Rating: 4.1 / 5 (62 voted)

Reviews: 93% of readers found this page helpful

Author information

Name: Corie Satterfield

Birthday: 1992-08-19

Address: 850 Benjamin Bridge, Dickinsonchester, CO 68572-0542

Phone: +26813599986666

Job: Sales Manager

Hobby: Table tennis, Soapmaking, Flower arranging, amateur radio, Rock climbing, scrapbook, Horseback riding

Introduction: My name is Corie Satterfield, I am a fancy, perfect, spotless, quaint, fantastic, funny, lucky person who loves writing and wants to share my knowledge and understanding with you.