Common IBS Medications

• Everyone’s IBS is managed a little differently, so there are many different types of IBS medications (and I am adding more as I go) so if it isn’t on here - it’s not personal!

• As discussed here, sometimes taking both medications at the same time can decrease the effifcacy of one of the other, or make things a little funky with your blood work.

• It’s important to let all of the prescribing doctors know the pertinent medications you are on for this reason (i.e, tell your IBS GI doc you’re on PrEP if you feel safe doing so, tell your prescribing doctor for PrEP your IBS medications, etc)

Alosetron (Lotronex)

• For IBS-D

• Relaxes the colon and slow the movement of waste through the lower bowel.

• Alosetron is intended only for severe cases of diarrhea-predominant IBS in cisgender women who haven't responded to other treatments. It is not approved for use by cisgender men.

• Alosetron has been linked to rare but important side effects, so it only should be considered when other treatments aren't successful.

• No interactions with Truvada or Descovy!

Eluxadoline (Viberzi)

• For IBS-D

• Eluxadoline can ease diarrhea by reducing muscle contractions and fluid secretion in the intestine.

• Helps increase muscle tone in the rectum.

• No interaction with Truvada, but a minor interaction with Descovy.

• When combined with Descovy, the concentration in your serum/blood of one half of the medicine (Tenofofivir) may be increased due to how the efflux pumps that metabolize the drug work.

• This may result in altered clinical efficacy (may not work as well) and increased risk for developing drug-related adverse reactions.

Rifaximin (Xifaxan)

• An antibiotic that can decrease bacterial overgrowth and diarrhea.

• No interactions with Truvada or Descovy! (obviously consult your doctor, etc etc this isn’t medical advice)

Lubiprostone (Amitiza)

• For IBS-C

• Can increase fluid secretion in the small intestine to help with the passage of stool.

• It's approved for cisgender women who have IBS with constipation, and is generally prescribed only for cisgender women with severe symptoms that haven't responded to other treatments (YMMV - speak to your provider!)

• Minor interaction with Truvada.

• When combined with Truvada, it may decrease the excretion rate (how fast your body clears the Amitiza from your system) of Lubiprostone which could result in a higher serum level of the medication.

• It is renally processed (goes through your kidneys) so if you have a history of kidney injury, your doctor will be aware of this and make sure your kidneys are all good.

• TLDR it’s good to be aware that the decreased renal excretion of the affected drug (Amitzia) may increase drug concentrations, leading to an elevated risk for drug-related adverse effects.

• There is a moderate interaction with Descovy.

• When taken with Descovy, the serum concentration (the levels of Descovy in your blood) ocan be increased.

• This is because they are both secreted by the kidneys, so taking both drugs that may that reduce renal function and compete for active tubular secretion may increase concentrations of Descovy and other renally eliminated drugs.

Linaclotide (Linzess)

• For IBS-C.

• Linaclotide also can increase fluid secretion in your small intestine to help you pass stool.

• Linaclotide can cause diarrhea, but taking the medicine 30 to 60 minutes before eating might help.

• No interactions with Truvada or Descovy!

Low Dose TCAs (Amitriptyline, Desipramine)

• Used for both types of IBS to control symptoms such as pain, diarrhea and a relief of global (all symptoms, such as abominal pain, abdominal distention, satisfaction with bowel habits, impact of IBS symptoms on quality of life, etc)

• Minor interaction with Truvada.

• When taken with Truvada, it may decrease the excretion rate (how much your body gets rid of) of Amitriptyline which could result in a higher serum level (how much of the medicine is in your blood).

• This is because they are renally (kidney) impacting medications, so it’s just important that you keep an eye on that!

• Moderate interaction with Descovy.

• When taking Descovy and Amitriptyline. together, the serum concentration of Descovy can be increased when it is combined with Amitriptyline.

• This is because it is filtered through the kidneys, similar to medicines from above!

• Because Descovy is primarily excreted by the kidneys by taking them at the same time with drugs that reduce renal function or compete for active tubular secretion may increase concentrations of Descovy and other renally eliminated drugs.

• This may increase the risk of adverse reactions.

• The key word in all of this is MAY, it’s not 100% - just increases the burden on the kidneys, especially if you have a history of kidney issues. For most people, it’s fine - talk to your doctor!

Colestipol

• Bile acid sequestering medication used in IBS-D

• No interactions with Truvada or Descovy!

Antispasmodics (Bentyl/Dicyclomine, Hyoscyamine)

• fairly self explanatory, but used for cramping/pain (anti-spasm)

• Bentyl (Dicylcomine) has no interactions with Truvada.

• Bentyl has a moderate interaction with Descovy.

• Similar to above, the serum concentration of Descovy can be increased when it is combined with Dicyclomine.

• This is because Descovy is secreted by the kidneys, taking these both with other medications that reduce renal function or compete for active tubular secretion may increase concentrations of Descovy and other renally eliminated drugs and this may increase the risk of adverse reactions.

• No interactions between Hyoscyamine and Descovy!

• No interactions between Hyoscyamine and Truvada!

Loperamide (Immodium)

• we know this one!

• For IBS-D

• Loperamide has a moderate interaction with Truvada.

• This is similar to above, but with a different mechanism!

• The serum concentration of Loperamide (Imodium) can be increased when it is combined with Truvada.

• The concentration of Immodium may increase due to competition among the substrates for the p-gp transporter (a molecular machine in your body the medicine uses to get where its going)

• This may result in drug toxicity and serious conditions such as excessive bleeding, cardiac conduction defects or organ toxicity, among many other effects.

• So definitely ask your doctor on this one!

• No interactions with Descovy!

From DrugBank, a database used for drug discovery, clinical research and academic research.

Knox C, Wilson M, Klinger CM, et al. DrugBank 6.0: the DrugBank Knowledgebase for 2024. Nucleic Acids Res. 2024 Jan 5;52(D1):D1265-D1275. doi: 10.1093/nar/gkad976.

Law V, Knox C, Djoumbou Y, Jewison T, Guo AC, Liu Y, Maciejewski A, Arndt D, Wilson M, Neveu V, Tang A, Gabriel G, Ly C, Adamjee S, Dame ZT, Han B, Zhou Y, Wishart DS. DrugBank 4.0: shedding new light on drug metabolism. Nucleic Acids Res. 2014 Jan 1;42(1):D1091-7.

Wishart DS, Feunang YD, Guo AC, Lo EJ, Marcu A, Grant JR, Sajed T, Johnson D, Li C, Sayeeda Z, Assempour N, Iynkkaran I, Liu Y, Maciejewski A, Gale N, Wilson A, Chin L, Cummings R, Le D, Pon A, Knox C, Wilson M. DrugBank 5.0: a major update to the DrugBank database for 2018. Nucleic Acids Res. 2017 Nov 8. doi: 10.1093/nar/gkx1037.

Wishart DS, Knox C, Guo AC, Cheng D, Shrivastava S, Tzur D, Gautam B, Hassanali M. DrugBank: a knowledgebase for drugs, drug actions and drug targets. Nucleic Acids Res. 2008 Jan;36(Database issue):D901-6.

Knox C, Law V, Jewison T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS. DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Nucleic Acids Res. 2011 Jan;39(Database issue):D1035-41.

PubMed: 21059682