para-aminosalicylic acid at a glance
Medicine class
Bacteriostatic antimycobacterial treatment.
Licensed role
Part of combination treatment for multidrug-resistant tuberculosis when other effective options cannot be assembled.
Form
Gastro-resistant oral granules that must remain intact.
Licensed age
Adults and children aged 28 days and older.
What is para-aminosalicylic acid used for?
The selected UK product is licensed only as part of an appropriate combination treatment for multidrug-resistant tuberculosis.
Adults and children aged 28 days and older when resistance or tolerability means that an effective treatment combination cannot otherwise be formed.
How does para-aminosalicylic acid work?
Para-aminosalicylic acid slows the growth of Mycobacterium tuberculosis rather than directly killing it. It resembles para-aminobenzoic acid and disrupts bacterial folate production, although its precise molecular target remains uncertain.
How to take para-aminosalicylic acid
Follow the specialist team's instructions. The granules may be taken with food and must be swallowed immediately after mixing, while still intact.
Mix with orange or tomato juice, swirl to suspend the granules and drink immediately.
Rinse any remaining granules from the glass with a little more liquid and swallow them.
For children, prescribed quantities may be measured with the supplied spoon and sprinkled onto apple sauce or yogurt.
Do not dissolve, crush or chew the granules because this damages their gastro-resistant coating.
Do not use a swollen sachet or granules that have turned dark brown or purple.
Empty granule shells may be visible in stools; this is expected.
para-aminosalicylic acid side effects
Common or expected effects
- Nausea, vomiting, abdominal pain, bloating, diarrhoea or soft stools
- Giddiness or problems with balance
- Skin redness, hypersensitivity or rash
Get urgent medical advice
- Rash or fever, particularly early in treatment, which may precede a serious hypersensitivity or liver reaction
- Dark urine, pale stools, jaundice, marked tiredness or abdominal pain suggesting hepatitis
- Bleeding from the digestive tract
- Unusual bruising, frequent infections or severe weakness, which may indicate a blood-cell disorder
- Symptoms of an underactive thyroid, particularly in people living with HIV or taking ethionamide or prothionamide
para-aminosalicylic acid in pregnancy
Human pregnancy information is limited, and the UK product is not recommended during pregnancy or for women who could become pregnant and are not using contraception. It should be considered only when clearly needed following specialist assessment; tuberculosis treatment should not be changed without the treating team.
para-aminosalicylic acid while breastfeeding
Para-aminosalicylic acid passes into breast milk, and its effects on breastfed infants are insufficiently understood. The UK product should not be used while breastfeeding; specialist advice is needed before changing either feeding plans or tuberculosis treatment.
para-aminosalicylic acid interactions
Tell the tuberculosis team about all prescribed, non-prescribed and complementary treatments. Relevant interactions include:
Vitamin B12
Para-aminosalicylic acid can reduce absorption, potentially causing clinically important deficiency during extended treatment.
Digoxin
Absorption may be reduced, so serum digoxin concentrations should be monitored.
Ethionamide
The combination may worsen gastrointestinal and liver-related adverse effects; the regimen requires specialist review if these become significant.
Diphenhydramine
It reduces gastrointestinal absorption of para-aminosalicylic acid and should not be used at the same time.
Common questions about para-aminosalicylic acid
Answers are fully visible for fast scanning and source review.
Why is para-aminosalicylic acid combined with other tuberculosis treatments?
It is bacteriostatic and is licensed as one component of a combination for multidrug-resistant tuberculosis, rather than as treatment on its own.
Can para-aminosalicylic acid granules be crushed or chewed?
No. Crushing or chewing damages the gastro-resistant coating and may alter absorption and increase stomach irritation.
Why can para-aminosalicylic acid granules appear in stools?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.