I feel weak after injection

Last week I got an injection on the buttocks. But now I feel weak in the leg. Was I given an expired drug or what?

— Akiiki Nyarwa

Dear Akiiki: Many Ugandans prefer injections to other forms of medication. However drugs given orally, rectally, under the skin or tongue will reach their intended ailing area except in special circumstances such as destruction by the digestive system, the subject is vomiting.
Nerves near the outside may be injured by injections. The injury may be from the needle itself, or by the substance injected and that is why quinine injections are no longer given in the buttocks but in a vein through a sugar drip if one is not diabetic (quinine reduces blood sugar).

Injections are frequently given in a muscle (intramuscular route of administration) of which the bum (gluteal muscles) or upper arm (deltoid muscles) are commonly used. Gluteal injections are more commonly used in both children and adults. Deltoid injections are more frequently used in adults and for vaccinations making sure one avoids the very upper areas which can result in bad scars (keloids) or injury of a nerve that goes around the arm.
Gluteal injections are traditionally placed in the upper and outer area of the buttocks to avoid the sciatic nerve. When injections are not strictly in this quadrant, the sciatic nerve may be injured causing the foot to slap the ground while walking (foot drop) or at worst weakness in the leg. In those who have lost a lot of weight (such as old age, cancer, prolonged bed rest) even properly placed injections can still cause nerve damage because the muscle mass is much reduced, causing the needle to be deeper than usual. Another risk factor is when injections are administered when patients twist over in bed. Also women with big buttocks may distort their anatomy while lying down and this is why medical workers prefer to give some people injections on the buttocks while standing or lying on the side.
You need to visit your doctor again for advice.