Can I take Levothyroxine and Promethazine together?

Perché succede

Levothyroxine is a synthetic version of the thyroid hormone T4. Promethazine is an antihistamine with 'anticholinergic' properties. While they do not interfere with how each other is absorbed or broken down by the body, both can influence heart rate. In patients with excessive thyroid hormone levels, promethazine could potentially contribute to a fast or irregular heartbeat.

It is generally safe to take these two medicines together. Ensure you take your levothyroxine at the same time every day (usually in the morning on an empty stomach). If you experience any heart palpitations, chest pain, or unusual restlessness while taking promethazine, contact your doctor. Always ensure your thyroid levels are being monitored regularly by your GP.

Heart conditions (e.g. angina, heart failure)

If you have a heart condition, your dose must be started very low and increased slowly. Contact your doctor immediately if you experience chest pain or palpitations, as levothyroxine increases the workload on your heart.

Breathing problems (Asthma, COPD, Sleep Apnoea)

Promethazine can cause severe breathing difficulties and should be avoided if you have serious lung conditions or sleep apnoea.

Glaucoma and Prostate issues

Do not use promethazine if you have narrow-angle glaucoma or an enlarged prostate, as it can cause a sudden increase in eye pressure or prevent you from passing urine.

Interaction with supplements (Calcium/Iron)

Do not take calcium tablets, iron supplements, or multivitamins at the same time as levothyroxine. You must leave a gap of at least 4 hours between these supplements and your levothyroxine to ensure the medicine works.

Diabete

La levotiroxina può aumentare i livelli di zucchero nel sangue. Se hai il diabete, devi monitorare più attentamente la glicemia quando inizi o cambi la dose, poiché potrebbe essere necessario aumentare la tua terapia per il diabete.

Alcol

It is best to avoid or strictly limit alcohol when taking promethazine. Alcohol significantly increases the sedative effects of this medicine, making you much more drowsy and increasing the risk of breathing difficulties or loss of consciousness.

It is best to avoid or strictly limit alcohol while taking levothyroxine. While there is no direct chemical reaction, alcohol can affect thyroid function and may worsen symptoms like tiredness or mood changes.

Timing of dose and food/drink

Take your levothyroxine on an empty stomach, at least 30 to 60 minutes before breakfast or any caffeine. Food, milk, and coffee prevent the medicine from being absorbed properly.

Caffeina (Caffè/Tè)

Caffeine can significantly reduce the amount of levothyroxine your body absorbs. You should wait at least 30 to 60 minutes after taking your tablet before drinking coffee or tea.

Prodotti lattiero-caseari (Latte, Yogurt, Formaggio)

Avoid consuming dairy products at the same time as your levothyroxine. Calcium found in dairy can interfere with how your body absorbs the medicine, making it less effective. It is best to wait at least 4 hours between taking levothyroxine and consuming dairy.

Prodotti a base di soia

Soya can interfere with the absorption of levothyroxine. If you regularly eat or drink soya products, your doctor may need to monitor your thyroid levels more closely. Avoid consuming soya at the same time as your dose.

Kelp and Seaweed

These foods are naturally high in iodine. Too much iodine can interfere with your thyroid treatment and make your condition worse.

Alimenti ricchi di fibre

A diet very high in fibre can reduce the absorption of levothyroxine. If you significantly change your fibre intake, inform your doctor as your dose may need adjusting.

Taking multiple medicines? Our Controllo Interazioni Farmaci helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Avvertenza

Queste informazioni sono solo a scopo educativo generale e non devono essere considerate un sostituto del consiglio medico professionale. Consultate sempre il vostro medico di base, farmacista o un altro professionista sanitario qualificato prima di prendere decisioni sui vostri farmaci. Le circostanze individuali possono variare, e solo un professionista sanitario che conosce la vostra storia medica può fornire una guida personalizzata.